r340744 removed pfind_locked() and replaced the pfind_locked() call in the NFSv4 client with pfind().
This is incorrect, since the call in the NFSv4 client must be done with a mutex held and _pfind() currently
uses an "sx" lock for the pid hash list.
Although mjg@ has suggested other ways to implement this without using any veriant of pfind(), those
suggestions will take time to work out (and may not be practicable). As such, this patch replaces pfind()
with an NFSv4 client custom version that does not do any locking and replaces the acquisition of the "allproc"
lock with the acquisition of all the pidhashtbl_locks.
Since this is only done once/sec, acquiring all the locks shouldn't be a serious performance problem.