gif2webp: Move GIF decoding related code to a support library.

Change-Id: Ifa5e663eb0db7e1e08174fe6608bd45950281abb

makefile.unix

@@ -181,6 +181,9 @@ EX_FORMAT_DEC_OBJS = \
 EX_UTIL_OBJS = \
     examples/example_util.o \
 
+GIFDEC_OBJS = \
+    examples/gifdec.o \
+
 MUX_OBJS = \
     src/mux/anim_encode.o \
     src/mux/muxedit.o \
@@ -258,6 +261,7 @@ OUTPUT = $(OUT_LIBS) $(OUT_EXAMPLES)
 ifeq ($(MAKECMDGOALS),clean)
   OUTPUT += $(EXTRA_EXAMPLES)
   OUTPUT += src/demux/libwebpdemux.a src/mux/libwebpmux.a
+  OUTPUT += examples/libgifdec.a
 endif
 
 ex: $(OUT_EXAMPLES)
@@ -277,6 +281,7 @@ src/utils/bit_writer.o: src/utils/endian_inl.h
 	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 examples/libexample_util.a: $(EX_UTIL_OBJS)
+examples/libgifdec.a: $(GIFDEC_OBJS)
 src/libwebpdecoder.a: $(LIBWEBPDECODER_OBJS)
 src/libwebp.a: $(LIBWEBP_OBJS)
 src/mux/libwebpmux.a: $(LIBWEBPMUX_OBJS)
@@ -287,7 +292,7 @@ src/demux/libwebpdemux.a: $(LIBWEBPDEMUX_OBJS)
 
 examples/cwebp: examples/cwebp.o $(EX_FORMAT_DEC_OBJS)
 examples/dwebp: examples/dwebp.o
-examples/gif2webp: examples/gif2webp.o
+examples/gif2webp: examples/gif2webp.o $(GIFDEC_OBJS)
 examples/vwebp: examples/vwebp.o
 examples/webpmux: examples/webpmux.o
 
@@ -295,7 +300,7 @@ examples/cwebp: examples/libexample_util.a src/libwebp.a
 examples/cwebp: EXTRA_LIBS += $(CWEBP_LIBS)
 examples/dwebp: examples/libexample_util.a src/libwebpdecoder.a
 examples/dwebp: EXTRA_LIBS += $(DWEBP_LIBS)
-examples/gif2webp: examples/libexample_util.a
+examples/gif2webp: examples/libexample_util.a examples/libgifdec.a
 examples/gif2webp: src/mux/libwebpmux.a src/libwebp.a
 examples/gif2webp: EXTRA_LIBS += $(GIF_LIBS)
 examples/gif2webp: EXTRA_FLAGS += -DWEBP_HAVE_GIF