Add support for GIF output using cgif in prebuilt binaries

test/leak/leak.sh

@@ -8,7 +8,7 @@ fi
 curl -s -o ./test/leak/libvips.supp https://raw.githubusercontent.com/libvips/libvips/master/suppressions/valgrind.supp
 
 for test in ./test/unit/*.js; do
-  G_SLICE=always-malloc G_DEBUG=gc-friendly valgrind \
+  G_SLICE=always-malloc G_DEBUG=gc-friendly VIPS_LEAK=1 valgrind \
     --suppressions=test/leak/libvips.supp \
     --suppressions=test/leak/sharp.supp \
     --gen-suppressions=yes \

test/leak/sharp.supp

@@ -225,14 +225,10 @@
   fun:FcInitLoadConfigAndFonts
 }
 {
-  leak_fontconfig_doContent
+  leak_fontconfig_XML_ParseBuffer
   Memcheck:Leak
   match-leak-kinds: definite
-  fun:malloc
   ...
-  fun:doContent
-  fun:doProlog
-  fun:prologInitProcessor
   fun:XML_ParseBuffer
   obj:*/libfontconfig.so.*
 }