re PR c++/63658 (Using class reference as template parameter causes compilation to fail)

	PR c++/63658
	* pt.c (convert_nontype_argument): Call convert_from_reference.
	(check_instantiated_arg): Don't be confused by reference refs.
	(unify): Look through reference refs on the arg, too.
	* mangle.c (write_template_arg): Look through reference refs.

From-SVN: r217900