shutdown: set always_reopen_console

Back in v232 systemd-shutdown would log to /dev/console. However after
the addition of always_reopen_console (v233) it would log to STDERR.
This caused some debugging issues as container systemd-shutdown logs
weren't being logged to console as the arg `--log-target=console` suggested.

Since it appears that always_reopen_console was intended for pid1, set
it in systemd-shutdown as well so logs will go to /dev/console.

src/shutdown/shutdown.c

@@ -322,6 +322,9 @@ int main(int argc, char *argv[]) {
         log_set_prohibit_ipc(true);
         log_parse_environment();
 
+        if (getpid_cached() == 1)
+                log_set_always_reopen_console(true);
+
         r = parse_argv(argc, argv);
         if (r < 0)
                 goto error;