When the screen is locked using ext_session_lock, killing swaylock will
leave the session locked. This is normally desirable if the kill is due
to the OOM killer or swaylock crashing, but can be undesirable if an
unlock is desired. This adds a signal handler for SIGUSR1 if using
ext_session_lock.
This implements a simpler version of the wlroots logger for swaylock.
With this logger, the dependency on wlroots can be dropped. This also
adds a debug flag and disables debugging output by default
