* langhooks-def.h (LANG_HOOKS_HASH_TYPES): New macro and hook.
	* langhooks.h (struct lang_hooks_for_types): New field hash_types.
	* tree.c (debug_no_type_hash): Deleted.
	(type_hash_canon): Abort if passed a variant.
	Check lang_hooks.types.hash_types.
	(build_type_no_quals): Copy mode of POINTER_TYPE and REFERENCE_TYPE.
	(build_array_type): Remove unnecessary allocation of pointer type.
	(build_complex_type): Properly qualify resulting type.

	* ada/decl.c (debug_no_type_hash): Remove.
	(gnat_to_gnu_entity, case E_Array_Type): Don't set and clear it.
	* ada/misc.c (LANG_HOOK_HASH_TYPE): Redefine.

From-SVN: r79684