libraries/wxWidgets: Autodetect NanoSVG.

Signed-off-by: Willy Sudiarto Raharjo <willysr@slackbuilds.org>

libraries/wxWidgets/README

@@ -5,6 +5,13 @@ controls and utilities.
 webkit2gtk is an optional dependency of this package. This will
 provide webview support.
 
+nanosvg is another optional dependency. By default, the
+SlackBuild script checks for the nanosvg system headers and
+disables SVG support if they are not found; you can force
+different behavior (e.g. using wxWidgets' internal copy of
+nanosvg, or always disabling SVG support) with the "NANOSVG"
+environment variable (see wxWidgets.SlackBuild for details).
+
 Notes:
 
 1. This package is NOT built using --enable-stl by default.

libraries/wxWidgets/wxWidgets.SlackBuild

@@ -76,6 +76,15 @@ else
   wk="OFF"
 fi
 
+# BCS: check for NanoSVG
+test -f /usr/include/nanosvg/nanosvg.h
+case "${NANOSVG:-auto}" in
+  no|off) nanosvg=OFF ;;
+  yes|on) [ $? = 0 ] && nanosvg=sys || nanosvg=builtin ;;
+  auto) [ $? = 0 ] && nanosvg=sys || nanosvg=OFF ;;
+  internal) nanosvg=builtin ;;
+esac
+
 set -e
 
 rm -rf $PKG
@@ -108,7 +117,7 @@ cmake -B build-gtk3 \
     -DwxUSE_LIBTIFF=sys \
     -DwxUSE_LIBLZMA=sys \
     -DwxUSE_LIBMSPACK=ON \
-    -DwxUSE_NANOSVG=OFF \
+    -DwxUSE_NANOSVG=$nanosvg \
     -DwxUSE_STL=$stl \
     -DwxUSE_WEBVIEW_WEBKIT=$wk \
     -DwxUSE_PRIVATE_FONTS=ON \