libungif: convert old-style hook to new-style hook

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libungif/libungif.mk

@@ -17,8 +17,10 @@ LIBUNGIF_BINS = gif2epsn gif2ps gif2rgb gif2x11 gifasm gifbg gifburst gifclip \
 		gifrsize gifspnge giftext gifwedge icon2gif raw2gif rgb2gif   \
 		text2gif
 
-$(eval $(call AUTOTARGETS,package,libungif))
-
-$(LIBUNGIF_HOOK_POST_INSTALL):
+define LIBUNGIF_BINS_CLEANUP
 	rm -f $(addprefix $(TARGET_DIR)/usr/bin/,$(LIBUNGIF_BINS))
-	touch $@
+endef
+
+LIBUNGIF_POST_INSTALL_TARGET_HOOKS += LIBUNGIF_BINS_CLEANUP
+
+$(eval $(call AUTOTARGETS,package,libungif))