Rename dirlink to gitlink.

Git changed from dirlink to gitlink in
302b9282c9ddfcc704ca759bdc98c1d5f75eba2f.

Signed-off-by: Jeffrey C. Ollie <jeff@ocjtech.us>
diff --git a/html.c b/html.c
index 33a956f..76fa6c4 100644
--- a/html.c
+++ b/html.c
@@ -158,7 +158,7 @@
 		html("d");
 	else if (S_ISLNK(mode))
 		html("l");
-	else if (S_ISDIRLNK(mode))
+	else if (S_ISGITLINK(mode))
 		html("m");
 	else
 		html("-");