Use type_hash_eq langhook in check_qualified_type.

Use type_hash_eq langhook in check_qualified_type.

gcc/
	* tree.c (check_lang_type): New.
	(check_qualified_type): Use it.
	(check_aligned_type): Use it.
	* tree.h: Declare it.
gcc/cp/
	* tree.c (cp_check_qualified_type): Call check_base_type instead
	of check_qualified_type.
	(cxx_type_hash_eq): Check ref-qualifiers.
	* typeck.c (apply_memfn_quals): No need to mess with TYPE_CANONICAL.

From-SVN: r241831