(Makefiles): PATCH to include libcpp and libiberty in GCC etags

	gcc/c/
	* Make-lang.in (c.tags): Also include libcpp TAGS.
	gcc/cp/
	* Make-lang.in (c++.tags): Also include libcpp TAGS.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@229504 138bc75d-0d04-0410-961f-82ee72b054a4