darwin notify don't recurse on vcache lock

darwin notify don't recurse on vcache lock

afs_vop_access->afs_VerifyVCache2->afs_GetVCache->afs_FetchStatus->
afs_Analyze->afs_NotifyUser can recurse and try to notify us. Don't
worry about it; we're best-effort.

we lack a lock primitive to see if we own this lock.

Change-Id: Ibc0c8a8164a95f0d268e5f1f42a62c3a28c4ab9d
Reviewed-on: http://gerrit.openafs.org/2081
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>