util: Don't use rx-internal locking macros

util: Don't use rx-internal locking macros

The MUTEX_INIT, MUTEX_ENTER, MUTEX_EXIT and MUTEX_DESTROY macros
are intended for RX internal use only (they're an abstraction
interface so that the same locking code can be used in userspace and
in the kernel). They aren't appropriate for general purpose use.

Just use pthread calls directly for the serverLog locks.

Change-Id: I8373eaa097c36f7d3a4c9b0501fc5e897372582e
Reviewed-on: http://gerrit.openafs.org/8031
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>