Fix dependency on libungif

package/directfb/directfb.mk

@@ -84,6 +84,7 @@ endif
 
 ifeq ($(BR2_PACKAGE_DIRECTFB_GIF),y)
 DIRECTFB_GIF:=--enable-gif
+DIRECTFB_DEP+= libungif
 else
 DIRECTFB_GIF:=--disable-gif
 endif