gcc/
	* doc/md.texi: Describe the use of match_tests in attribute tests.
	* rtl.def (MATCH_TEST): Update commentary.
	* genattrtab.c (attr_copy_rtx, check_attr_test, clear_struct_flag)
	(write_test_expr, walk_attr_value): Handle MATCH_TEST.

From-SVN: r178388