t/helper: allow chmtime to print verbosely without modifying mtime

The `test-tool chmtime` helper allows us to both read and modify the
modification time of files. But while it is possible to only read the
mtimes of a file via `--get`, it is not possible to read the mtimes
and report them together with their respective file paths via the
`--verbose` flag without also modifying the mtime at the same time.

Fix this so that it is possible to call `test-tool chmtime --verbose
<files>...` without modifying any mtimes.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

t/helper/test-chmtime.c

@@ -94,7 +94,7 @@ int cmd__chmtime(int argc, const char **argv)
 	if (timespec_arg(argv[i], &set_time, &set_eq)) {
 		++i;
 	} else {
-		if (get == 0) {
+		if (get == 0 && verbose == 0) {
 			fprintf(stderr, "Not a base-10 integer: %s\n", argv[i] + 1);
 			goto usage;
 		}