main: when transitioning from initrd to the main system log to kmsg

main: when transitioning from initrd to the main system log to kmsg

When the new PID is invoked the journal socket from the initrd might
still be around. Due to the default log target being journal we'd log to
that initially when the new main systemd initializes even if the kernel
command line included a directive to redirect systemd's logging
elsewhere.

With this fix we initially always log to kmsg now, if we are PID1, and
only after parsing the kernel cmdline try to open the journal if that's
desired.

(The effective benefit of this is that SELinux performance data is now
logged again to kmsg like it used to be.)