PR ada/21952
	* gigi.h (gnat_internal_attribute_table): Declare.
	* misc.c (LANG_HOOKS_ATTRIBUTE_TABLE): Define to above.
	* utils.c (gnat_internal_attribute_table): New global variable.
	(builtin_function): Always call decl_attributes on the builtin.
	(handle_const_attribute): New static function.
	(handle_nothrow_attribute): Likewise.

From-SVN: r116926