re PR c++/16964 (ICE in cp_parser_class_specifier due to redefinition)

re PR c++/16964 (ICE in cp_parser_class_specifier due to redefinition)

	PR c++/16964
	* parser.c (cp_parser_class_specifier): Robustify.

	PR c++/16904
	* pt.c (tsubst_copy_and_build): Complain about invalid
	qualification.

	PR c++/16929
	* pt.c (tsubst_default_argument): Clear out current_class_ptr and
	current_class_ref while tsubsting.

	PR c++/16964
	* g++.dg/parse/error16.C: New test.

	PR c++/16904
	* g++.dg/template/error14.C: New test.

	PR c++/16929
	* g++.dg/template/error15.C: New test.

From-SVN: r85824