build: make svg buttons optional

Add -Dsvg=disabled to your meson setup/configure command to disable svg
buttons even if the correct version of librsvg is available.

Note that regardless of this patch and the value of the 'svg' variable,
the build will gracefully fall back to not using librsvg if the correct
version is not available.

Helped-by: @01micko

meson.build

@@ -79,7 +79,12 @@ have_xwayland = xcb.found() and wlroots_has_xwayland
 conf_data = configuration_data()
 conf_data.set10('HAVE_XWAYLAND', have_xwayland)
 
-conf_data.set10('HAVE_RSVG', svg.found())
+if get_option('svg').disabled()
+  have_rsvg = false
+else
+  have_rsvg = svg.found()
+endif
+conf_data.set10('HAVE_RSVG', have_rsvg)
 
 msgfmt = find_program('msgfmt', required: get_option('nls'))
 if msgfmt.found()
@@ -109,7 +114,7 @@ labwc_deps = [
   math,
   png,
 ]
-if svg.found()
+if have_rsvg
   labwc_deps += [
     svg,
   ]

meson_options.txt

@@ -1,3 +1,4 @@
 option('man-pages', type: 'feature', value: 'auto', description: 'Generate and install man pages')
 option('xwayland', type: 'feature', value: 'auto', description: 'Enable support for X11 applications')
+option('svg', type: 'feature', value: 'enabled', description: 'Enable svg window buttons')
 option('nls', type: 'feature', value: 'auto', description: 'Enable native language support')

src/button/meson.build

@@ -4,7 +4,7 @@ labwc_sources += files(
   'common.c',
 )
 
-if svg.found()
+if have_rsvg
   labwc_sources += files(
     'button-svg.c',
   )