Teach runstatus about --untracked

Actually, teach runstatus what to do if it is not passed; it should not list
the contents of completely untracked directories, but only the name of that
directory (plus a trailing '/').

[jc: with comments by Jeff King to match hide-empty-directories
 behaviour of the original.]

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-runstatus.c

@@ -25,6 +25,8 @@ int cmd_runstatus(int argc, const char **argv, const char *prefix)
 		}
 		else if (!strcmp(argv[i], "--verbose"))
 			s.verbose = 1;
+		else if (!strcmp(argv[i], "--untracked"))
+			s.untracked = 1;
 		else
 			usage(runstatus_usage);
 	}