c++: fix injected friend of template class

c++: fix injected friend of template class

In working on fixing hiddenness, I discovered some suspicious code in
template instantiation.  I suspect it dates from when we didn't do the
hidden friend injection thing at all.  The xreftag finds the same
class, but makes it visible to name lookup.  Which is wrong.
hurrah, fixing a bug by deleting code!

	gcc/cp/
	* pt.c (instantiate_class_template_1): Do not repush and unhide
	injected friend.
	gcc/testsuite/
	* g++.old-deja/g++.pt/friend34.C: Check injected friend is still
	invisible.