1 GET_CONTROL_LOCK  
 Called by all EMU processes. This is the shutdown mechanism. EMU_CONTROL
 gets this lock in EX mode and all other processes attempt the same. If the 
 Control process ends (for any reason!) the lock is released to the next
 nest requestor. If any process (Other than control) receives this lock
 it exits. There are no inputs, outputs or returns from this routine.
