re PR c++/6936 (member "using" binds wrong)

	PR c++/6936
	PR c++/25994
	PR c++/26256
	PR c++/30195
	* search.c (lookup_field_1): Look through USING_DECL.
	(lookup_field_r): Call lookup_fnfields_slot instead of
	lookup_fnfields_1.
	* semantics.c (finish_member_declaration): Remove the check that
	prevents USING_DECLs from being verified by
	pushdecl_class_level. Call add_method for using declarations that
	designates functions if the using declaration is in a template
	class. Set DECL_IGNORED_P on class-scope using declarations.
	* typeck.c (build_class_member_access_expr): Handle USING_DECLs.
	* class.c (check_field_decls): Keep using declarations.
	(add_method): Remove two diagnostics about conflicting using
	declarations.
	* parser.c (cp_parser_nonclass_name): Handle USING_DECLs.
	* decl.c (start_enum): Call xref_tag whenever possible.
	* cp-tree.h (strip_using_decl): Declare, and reident the previous
	function.
	* name-lookup.c (strip_using_decl): New function.
	(supplement_binding_1): Call strip_using_decl on decl and
	bval. Perform most of the checks with USING_DECLs stripped.  Also
	check that the target decl and the target bval does not refer to
	the same declaration. Allow pushing an enum multiple times in a
	template class. Adjustment to diagnose using redeclarations. Call
	diagnose_name_conflict.
	(push_class_level_binding): Call strip_using_decl on decl and
	bval. Perform most of the checks with USING_DECLs stripped. Return
	true if both decl and bval refer to USING_DECLs and are dependent.
	(diagnose_name_conflict): New function.

From-SVN: r181359