PR c++/91844 - Implement CWG 2352, Similar types and reference binding.

PR c++/91844 - Implement CWG 2352, Similar types and reference binding.

	* call.c (reference_related_p): Use similar_type_p instead of
	same_type_p.
	(reference_compatible_p): Update implementation to match CWG 2352.
	* cp-tree.h (similar_type_p): Declare.
	* typeck.c (similar_type_p): New.

	* g++.dg/cpp0x/pr33930.C: Add dg-error.
	* g++.dg/cpp0x/ref-bind1.C: New test.
	* g++.dg/cpp0x/ref-bind2.C: New test.
	* g++.dg/cpp0x/ref-bind3.C: New test.
	* g++.old-deja/g++.pt/spec35.C: Remove dg-error.

From-SVN: r276058