diff -r ca825e816a50 -r 1ba637f64695 configure
--- a/configure	Wed Dec 31 16:32:36 2025 +0100
+++ b/configure	Wed Jan 21 21:25:32 2026 +0100
@@ -85,29 +85,32 @@
 printhelp()
 {
     echo "Usage: $0 [OPTIONS]..."
-    echo 'Configuration:'
+    if [ $has_overridable_config_vars__ -eq 1 ] ; then
+        echo
+        echo "Configuration:"
+    fi
 if true \
       ; then
     :
-    if test -z "$prefix__described__"; then
+    if [ -z "$prefix__described__" ] ; then
         prefix__described__=1
         cat << '__EOF__'
   --prefix                path prefix for architecture-independent files [/usr]
 __EOF__
     fi
-    if test -z "$exec_prefix__described__"; then
+    if [ -z "$exec_prefix__described__" ] ; then
         exec_prefix__described__=1
         cat << '__EOF__'
   --exec-prefix           path prefix for architecture-dependent files [PREFIX]
 __EOF__
     fi
-    if test -z "$libdir__described__"; then
+    if [ -z "$libdir__described__" ] ; then
         libdir__described__=1
         cat << '__EOF__'
   --libdir                object code libraries [EPREFIX/lib]
 __EOF__
     fi
-    if test -z "$includedir__described__"; then
+    if [ -z "$includedir__described__" ] ; then
         includedir__described__=1
         cat << '__EOF__'
   --includedir            C header files [PREFIX/include]
@@ -118,7 +121,7 @@
     && isplatform "freebsd" \
       ; then
     :
-    if test -z "$pkgconfigdir__described__"; then
+    if [ -z "$pkgconfigdir__described__" ] ; then
         pkgconfigdir__described__=1
         cat << '__EOF__'
   --pkgconfigdir          location of the *.pc files
@@ -129,7 +132,7 @@
       && notisplatform "freebsd" \
       ; then
     :
-    if test -z "$pkgconfigdir__described__"; then
+    if [ -z "$pkgconfigdir__described__" ] ; then
         pkgconfigdir__described__=1
         cat << '__EOF__'
   --pkgconfigdir          location of the *.pc files
@@ -139,7 +142,7 @@
 if true \
       ; then
     :
-    if test -z "$DOXYGEN__described__"; then
+    if [ -z "$DOXYGEN__described__" ] ; then
         DOXYGEN__described__=1
         cat << '__EOF__'
   --doxygen               path of the Doxygen executable
@@ -181,74 +184,79 @@
 touch "$TEMP_DIR/features"
 
 # config variables
+has_overridable_config_vars__=0
 if true \
       ; then
     :
-    if test -z "$prefix__initialized__"; then
+    if [ -z "$prefix__initialized__" ] ; then
+        has_overridable_config_vars__=1
         prefix__initialized__=1
         prefix='/usr'
     fi
-    if test -z "$exec_prefix__initialized__"; then
+    if [ -z "$exec_prefix__initialized__" ] ; then
+        has_overridable_config_vars__=1
         exec_prefix__initialized__=1
         exec_prefix=''
     fi
-    if test -z "$libdir__initialized__"; then
+    if [ -z "$libdir__initialized__" ] ; then
+        has_overridable_config_vars__=1
         libdir__initialized__=1
         libdir=''
     fi
-    if test -z "$includedir__initialized__"; then
+    if [ -z "$includedir__initialized__" ] ; then
+        has_overridable_config_vars__=1
         includedir__initialized__=1
         includedir=''
     fi
-    if test -z "$VERSION__initialized__"; then
+    if [ -z "$VERSION__initialized__" ] ; then
         VERSION__initialized__=1
         VERSION='4.0.0'
     fi
-    if test -z "$LIBVERSION__initialized__"; then
+    if [ -z "$LIBVERSION__initialized__" ] ; then
         LIBVERSION__initialized__=1
         LIBVERSION='7.0.0'
     fi
-    if test -z "$LIBVERSION_MAJOR__initialized__"; then
+    if [ -z "$LIBVERSION_MAJOR__initialized__" ] ; then
         LIBVERSION_MAJOR__initialized__=1
         LIBVERSION_MAJOR='7'
     fi
-    if test -z "$root_dir__initialized__"; then
+    if [ -z "$root_dir__initialized__" ] ; then
         root_dir__initialized__=1
         root_dir=`pwd`
     fi
-    if test -z "$build_dir__initialized__"; then
+    if [ -z "$build_dir__initialized__" ] ; then
         build_dir__initialized__=1
         build_dir='${root_dir}/build'
     fi
-    if test -z "$docs_dir__initialized__"; then
+    if [ -z "$docs_dir__initialized__" ] ; then
         docs_dir__initialized__=1
         docs_dir='${root_dir}/build/docs'
     fi
-    if test -z "$dist_dir__initialized__"; then
+    if [ -z "$dist_dir__initialized__" ] ; then
         dist_dir__initialized__=1
         dist_dir='${root_dir}/dist'
     fi
-    if test -z "$MKDIR__initialized__"; then
+    if [ -z "$MKDIR__initialized__" ] ; then
         MKDIR__initialized__=1
         MKDIR='/bin/mkdir -p'
     fi
-    if test -z "$RMFILE__initialized__"; then
+    if [ -z "$RMFILE__initialized__" ] ; then
         RMFILE__initialized__=1
         RMFILE='/bin/rm -f'
     fi
-    if test -z "$RMDIR__initialized__"; then
+    if [ -z "$RMDIR__initialized__" ] ; then
         RMDIR__initialized__=1
         RMDIR='/bin/rm -f -R'
     fi
-    if test -z "$COPYFILE__initialized__"; then
+    if [ -z "$COPYFILE__initialized__" ] ; then
         COPYFILE__initialized__=1
         COPYFILE='/bin/cp -f'
     fi
-    if test -z "$COPYALL__initialized__"; then
+    if [ -z "$COPYALL__initialized__" ] ; then
         COPYALL__initialized__=1
         COPYALL='/bin/cp -f -R'
     fi
-    if test -z "$SYMLINK__initialized__"; then
+    if [ -z "$SYMLINK__initialized__" ] ; then
         SYMLINK__initialized__=1
         SYMLINK='/bin/ln -s'
     fi
@@ -257,7 +265,8 @@
     && isplatform "freebsd" \
       ; then
     :
-    if test -z "$pkgconfigdir__initialized__"; then
+    if [ -z "$pkgconfigdir__initialized__" ] ; then
+        has_overridable_config_vars__=1
         pkgconfigdir__initialized__=1
         pkgconfigdir='${exec_prefix}/libdata/pkgconfig'
     fi
@@ -266,7 +275,8 @@
       && notisplatform "freebsd" \
       ; then
     :
-    if test -z "$pkgconfigdir__initialized__"; then
+    if [ -z "$pkgconfigdir__initialized__" ] ; then
+        has_overridable_config_vars__=1
         pkgconfigdir__initialized__=1
         pkgconfigdir='${libdir}/pkgconfig'
     fi
@@ -274,7 +284,8 @@
 if true \
       ; then
     :
-    if test -z "$DOXYGEN__initialized__"; then
+    if [ -z "$DOXYGEN__initialized__" ] ; then
+        has_overridable_config_vars__=1
         DOXYGEN__initialized__=1
         DOXYGEN=`command -v doxygen || echo '/bin/false'`
     fi
@@ -424,35 +435,32 @@
 
 
 # generate vars.mk
-cat > "$TEMP_DIR/vars.mk" << __EOF__
-prefix=$prefix
-exec_prefix=$exec_prefix
-libdir=$libdir
-includedir=$includedir
-VERSION=$VERSION
-LIBVERSION=$LIBVERSION
-LIBVERSION_MAJOR=$LIBVERSION_MAJOR
-root_dir=$root_dir
-build_dir=$build_dir
-docs_dir=$docs_dir
-dist_dir=$dist_dir
-MKDIR=$MKDIR
-RMFILE=$RMFILE
-RMDIR=$RMDIR
-COPYFILE=$COPYFILE
-COPYALL=$COPYALL
-SYMLINK=$SYMLINK
-pkgconfigdir=$pkgconfigdir
-DOXYGEN=$DOXYGEN
-__EOF__
-
+echo '# configuration' > "$TEMP_DIR/vars.mk"
+echo "prefix=$prefix" >> "$TEMP_DIR/vars.mk"
+echo "exec_prefix=$exec_prefix" >> "$TEMP_DIR/vars.mk"
+echo "libdir=$libdir" >> "$TEMP_DIR/vars.mk"
+echo "includedir=$includedir" >> "$TEMP_DIR/vars.mk"
+echo "VERSION=$VERSION" >> "$TEMP_DIR/vars.mk"
+echo "LIBVERSION=$LIBVERSION" >> "$TEMP_DIR/vars.mk"
+echo "LIBVERSION_MAJOR=$LIBVERSION_MAJOR" >> "$TEMP_DIR/vars.mk"
+echo "root_dir=$root_dir" >> "$TEMP_DIR/vars.mk"
+echo "build_dir=$build_dir" >> "$TEMP_DIR/vars.mk"
+echo "docs_dir=$docs_dir" >> "$TEMP_DIR/vars.mk"
+echo "dist_dir=$dist_dir" >> "$TEMP_DIR/vars.mk"
+echo "MKDIR=$MKDIR" >> "$TEMP_DIR/vars.mk"
+echo "RMFILE=$RMFILE" >> "$TEMP_DIR/vars.mk"
+echo "RMDIR=$RMDIR" >> "$TEMP_DIR/vars.mk"
+echo "COPYFILE=$COPYFILE" >> "$TEMP_DIR/vars.mk"
+echo "COPYALL=$COPYALL" >> "$TEMP_DIR/vars.mk"
+echo "SYMLINK=$SYMLINK" >> "$TEMP_DIR/vars.mk"
+echo "pkgconfigdir=$pkgconfigdir" >> "$TEMP_DIR/vars.mk"
+echo "DOXYGEN=$DOXYGEN" >> "$TEMP_DIR/vars.mk"
+echo >> "$TEMP_DIR/vars.mk"
 
 #
 # DEPENDENCIES
 #
 
-
-
 # create buffer for make variables required by dependencies
 echo > "$TEMP_DIR/make.mk"
 
@@ -1037,20 +1045,34 @@
 if [ -n "$TOOLCHAIN_CSTD" ]; then
     echo "  default C std:  $TOOLCHAIN_CSTD"
 fi
-echo
-echo "Config:"
-    printf '  %-16s' 'prefix:'
-    echo "$prefix"
-    printf '  %-16s' 'exec-prefix:'
-    echo "$exec_prefix"
-    printf '  %-16s' 'libdir:'
-    echo "$libdir"
-    printf '  %-16s' 'includedir:'
-    echo "$includedir"
-    printf '  %-16s' 'pkgconfigdir:'
-    echo "$pkgconfigdir"
-    printf '  %-16s' 'doxygen:'
-    echo "$DOXYGEN"
+if [ $has_overridable_config_vars__ -eq 1 ]; then
+    echo
+    echo "Config:"
+    if [ -n "$prefix__initialized__" ]; then
+        printf '  %-16s' 'prefix:'
+        echo "$prefix"
+    fi
+    if [ -n "$exec_prefix__initialized__" ]; then
+        printf '  %-16s' 'exec-prefix:'
+        echo "$exec_prefix"
+    fi
+    if [ -n "$libdir__initialized__" ]; then
+        printf '  %-16s' 'libdir:'
+        echo "$libdir"
+    fi
+    if [ -n "$includedir__initialized__" ]; then
+        printf '  %-16s' 'includedir:'
+        echo "$includedir"
+    fi
+    if [ -n "$pkgconfigdir__initialized__" ]; then
+        printf '  %-16s' 'pkgconfigdir:'
+        echo "$pkgconfigdir"
+    fi
+    if [ -n "$DOXYGEN__initialized__" ]; then
+        printf '  %-16s' 'doxygen:'
+        echo "$DOXYGEN"
+    fi
+fi
 echo
 echo "Features:"
 printf '  %-16s' 'api-docs:'