Fix PR c++/18969 (invalid return statement diagnosed too late)

Fix PR c++/18969 (invalid return statement diagnosed too late)

gcc/cp/ChangeLog:

	PR c++/18969
	* typeck.c (check_return_expr): Also do the basic return-value
	validity checking if processing_template_decl and yet types are
	not dependent.  Remove obsolete code.

gcc/testsuite/ChangeLog:

	PR c++/18969
	* g++.dg/template/pr18969.C: New test.
	* g++.dg/template/pr18969-2.C: New test.
	* g++.old-deja/g++.jason/overload.C: Remove return value in
	template function returning void.

From-SVN: r226236