re PR c++/50800 (Internal compiler error in finish_member_declarations, possibly related to may_alias attribute)

	PR c++/50800
	* tree.c (strip_typedefs): Add remove_attributes parm.
	(strip_typedefs_expr): Likewise.
	(apply_identity_attributes): New subroutine of strip_typedefs.
	* pt.c (canonicalize_type_argument): Let strip_typedefs handle attrs.
	(convert_nontype_argument, unify): Likewise.
	* cp-tree.h: Adjust.

From-SVN: r222530