This patch fixes merge_contexts_and_delete so it does not deadlock when hints are present.

Reason: when I re-engineered the merge_and_delete func to
reduce its lock time, I failed to notice that the 
functions it calls still also do locking as before.
This leads to deadlocks on dialplan reloads, when
there are actually living, subscribed hints registered
in the system.

While the reporter come across this problem while using
AEL, I might note that these deadlocks should also happen
if extensions.conf were used.

Here I added these routines to pbx.c:

ast_add_extension_nolock
add_pri_lockopt
ast_add_extension2_lockopt
find_context
add_hint_nolock

All of the above routines are static and restricted
to be used only within pbx.c, and more specifically
within the merge_contexts_and_delete routine.

They are pretty much the same as their counterparts
except they don't lock contexts or hints.

Most of them now do the real work of their
name-alike, with optional locking via extra arguments,
and are called by their name-alike. The goal was to
have the original functions so they would behave
exactly as before.

Both PJ and I tested these fixes, and the deadlocking
problem is no longer encountered.

(closes issue #14357)
Reported by: pj
Patches:
      14357.diff uploaded by murf (license 17)
Tested by: pj, murf



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@176943 65c4cc65-6c06-0410-ace0-fbb531ad65f3