pid1: make sure we look at /proc/1/cmdline when parsing config

In recent systemd-nspawn we wouldn't parse init args like systemd.log-level=debug.
This is because we wouldn't even look at /proc/1/cmdline.

$ systemd-nspawn -n cat /proc/1/stat
1 (cat) R 0 1 1 34816 ....
                ^^^^^
34816 is 136:0 a.k.a. /dev/pts/0.

src/basic/log.c

@@ -1101,9 +1101,10 @@ void log_parse_environment_realm(LogRealm realm) {
 
         const char *e;
 
-        if (get_ctty_devnr(0, NULL) < 0)
-                /* Only try to read the command line in daemons.  We assume that anything that has a controlling tty is
-                   user stuff. */
+        if (getpid_cached() == 1 || get_ctty_devnr(0, NULL) < 0)
+                /* Only try to read the command line in daemons. We assume that anything that has a
+                 * controlling tty is user stuff. For PID1 we do a special check in case it hasn't
+                 * closed the console yet. */
                 (void) proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX);
 
         e = getenv("SYSTEMD_LOG_TARGET");