Now we have log_set_prohibit_ipc(), let's use it to clarify that
systemd-shutdown is not expected to try and log via journald (which it is
about to kill). We avoided ever asking systemd-shutdown to do this, but
it's more convenient for the reader if they don't have to think about that.
In that sense, it's similar to using assert() to validate a function's
arguments.
/* journald will die if not gone yet. The log target defaults
* to console, but may have been changed by command line options. */
+ log_set_prohibit_ipc(true);
log_open();
umask(0022);