res_sorcery_memory_cache.c: Fix deadlock with scheduler.

res_sorcery_memory_cache.c: Fix deadlock with scheduler.

A deadlock can happen when a sorcery object is being expired from the
memory cache when at the same time another object is being placed into the
memory cache.  There are a couple other variations on this theme that
could cause the deadlock.  Basically if an object is being expired from
the sorcery memory cache at the same time as another thread tries to
update the next object expiration timer the deadlock can happen.

* Add a deadlock avoidance loop in expire_objects_from_cache() to check if
someone is trying to remove the scheduler callback from the scheduler.

ASTERISK-25441 #close

Change-Id: Iec7b0bdb81a72b39477727b1535b2539ad0cf4dc