package/libvips: add giflib optional dependency

giflib is an optional dependency which is enabled by default since
version 8.3.0 and
https://github.com/libvips/libvips/commit/d79407f285c768a7338e73ccfc6cf09480b95582

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit bd1a3a29debdd43e07ad34b29283be5515539013)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libvips/libvips.mk

@@ -40,6 +40,13 @@ LIBVIPS_DEPENDENCIES = \
 	host-pkgconf expat libglib2 \
 	$(TARGET_NLS_DEPENDENCIES)
 
+ifeq ($(BR2_PACKAGE_GIFLIB),y)
+LIBVIPS_CONF_OPTS += --with-giflib
+LIBVIPS_DEPENDENCIES += giflib
+else
+LIBVIPS_CONF_OPTS += --without-giflib
+endif
+
 ifeq ($(BR2_PACKAGE_GOBJECT_INTROSPECTION),y)
 LIBVIPS_CONF_OPTS += --enable-introspection
 LIBVIPS_DEPENDENCIES += gobject-introspection