Ensure that libg722.a gets rebuilt if one of the files changes

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@97650 65c4cc65-6c06-0410-ace0-fbb531ad65f3

codecs/Makefile

@@ -54,3 +54,5 @@ $(LIBG722):
 	@$(MAKE) -C g722 all
 
 $(if $(filter codec_g722,$(EMBEDDED_MODS)),modules.link,codec_g722.so): $(LIBG722)
+
+.PHONY: $(LIBG722)