Remove some bogus deadlock avoidance code from local_attended_transfer.

First of all, the code was unnecessary. The goal was to lock a channel
which was already locked. Second, the assumption of the deadlock avoidance
loop was that the sip_pvt was already locked and we were trying to get the
channel lock. The problem is that the sip_pvt was unlocked a few lines above.

Basically, I'm removing 5 lines of no-op.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@204530 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -20789,11 +20789,7 @@ static int local_attended_transfer(struct sip_pvt *transferer, struct sip_dual *
 		/* Transfer succeeded! */
 		const char *xfersound = pbx_builtin_getvar_helper(target.chan1, "ATTENDED_TRANSFER_COMPLETE_SOUND");
-		while (ast_channel_trylock(target.chan1)) {
-			sip_pvt_unlock(targetcall_pvt);
-			sched_yield();
-			sip_pvt_lock(targetcall_pvt);
-		}
+		/* target.chan1 was locked in get_sip_pvt_byid_locked */
 		ast_cel_report_event(target.chan1, AST_CEL_ATTENDEDTRANSFER, NULL, transferer_linkedid, target.chan2);
 		ast_channel_unlock(target.chan1);