7202da4491
sx lock. Trying to get the lock order between these locks was getting too complicated as the locking in wait1() was being fixed. - leavepgrp() now requires an exclusive lock of proctree_lock to be held when it is called. - fixjobc() no longer gets a shared lock of proctree_lock now that it requires an xlock be held by the caller. - Locking notes in sys/proc.h are adjusted to note that everything that used to be protected by the pgrpsess_lock is now protected by the proctree_lock.