re PR c++/21353 (rvalues should not be allowed to be default values for non const references in class functions.)

cp:
	PR c++/21353
	* g++.dg/template/defarg6.C: New.
testsuite:
	PR c++/21353
	* decl.c (check_default_argument): Don't check
	processing_template_decl or uses_template_parms here.
	(grokparms): Only call check_default_argument when not processing
	a template decl.
	* parser.c (cp_parser_late_parsing_default_arg): Call
	check_default_argument when not processing a template decl.

From-SVN: r105492