1.0.48.10: add deadlock detection to spinlocks and mutexes

1.0.48.10: add deadlock detection to spinlocks and mutexes

 Each thread gets a WAITING-FOR slot which holds the lock it is
 currently trying to acquire.

 After initial try at lock acquisition fails, we check for deadlocks:
 we look at the thread that owns the lock we want -> lock it is
 waiting for, etc, recursively, until we either bottom out or find
 someone waiting for us.

 Print thread as having state WAITING if it is waiting for a lock.

 Add a PRINT-OBJECT methods for MUTEXes and SPINLOCKs.

 SB-THREAD:THREAD-DEADLOCK-CYCLE contains a list of the
 threads and locks involved, so that the situation can be
 analyzed even afer a handler has broken the deadlock.