Implement using decls inside template functions.

Implement using decls inside template functions.

cp:
	Implement using decls inside template functions.
	* decl2.c (validate_nonmember_using_decl): Don't special case
	fake_std_node in the global namespace. Don't reject early when
	processing a template.
	(do_local_using_decl): Add to statement tree. Don't do further
	processing when building a template.
	* pt.c (tsubst_expr, DECL_STMT case): Deal with USING_DECLs.
testsuite:
	* g++.old-deja/g++.pt/using1.C: New test.

From-SVN: r40151