Use DIFF_XDL_SET/DIFF_OPT_SET instead of raw bit-masking

Signed-off-by: Keith Cascio <keith@cs.ucla.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.h b/diff.h
index 6703a4f..6616877 100644
--- a/diff.h
+++ b/diff.h
@@ -69,6 +69,9 @@
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)
 #define DIFF_OPT_CLR(opts, flag)    ((opts)->flags &= ~DIFF_OPT_##flag)
+#define DIFF_XDL_TST(opts, flag)    ((opts)->xdl_opts & XDF_##flag)
+#define DIFF_XDL_SET(opts, flag)    ((opts)->xdl_opts |= XDF_##flag)
+#define DIFF_XDL_CLR(opts, flag)    ((opts)->xdl_opts &= ~XDF_##flag)
 
 struct diff_options {
 	const char *filter;