afs: alloc openafs_lck_grp before osi_Init() on darwin

afs: alloc openafs_lck_grp before osi_Init() on darwin

Commit a27bed59cae1a4244429c752edfde0a8363c8a3b moved init_hckernel_init
to osi_Init. On Darwin (AFS_DARWIN80_ENV), MUTEX_INIT
(called by init_hckernel_init) uses openafs_lck_grp as the argument of
one of the functions called during the initialization of the mutex in
question. Since openafs_lck_grp was not allocated yet, we crash.

To fix this problem, call MUTEX_SETUP() before osi_Init() on Darwin.

Reviewed-on: https://gerrit.openafs.org/13065
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 8e740aed774d4507e656e6ae743f6c6fe6c0e356)

Change-Id: Ic1c58b5e2baeedd1cd24c364dd2907761064c8a9
Reviewed-on: https://gerrit.openafs.org/13115
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>