ls-files: require worktree when --deleted is given

The code will end up calling lstat() to check whether the
file still exists; obviously this doesn't work if we're not
in the worktree.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-ls-files.c

@@ -419,6 +419,7 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 		}
 		if (!strcmp(arg, "-d") || !strcmp(arg, "--deleted")) {
 			show_deleted = 1;
+			require_work_tree = 1;
 			continue;
 		}
 		if (!strcmp(arg, "-m") || !strcmp(arg, "--modified")) {