Fix Android.mk.

- You don't need to explicitly specify protobuf library; The library
  name has been changed and the build system automatically adds it.
- You can't have a file target $(LOCAL_BUILT_MODULE) depend on phony target
  launcher_protoutil_lib.
- "include $(call all-makefiles-under,$(LOCAL_PATH))" must be on the
  last line.

Change-Id: I0d7d7df555f53b5ee5ff2bc5fe2b9e58dbe8a9d5