util: always initialize the server log mutex
Be sure to always initialize the server log mutex. Use pthread_once to
ensure the mutex is initialized only once.
Before this change the server log mutex was not properly initialized
with pthread_mutex_init when logging to the syslog.
Change-Id: Ief2ee6b373f7309bc05061f7413b6ff623b86e31
Reviewed-on: https://gerrit.openafs.org/11717
Reviewed-by: Chas Williams <3chas3@gmail.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>