pjroject_bundled: Add already-destroyed check to tsx_timer_callback

There have been cases that when the transaction timer callback is called
the tsx is already destroyed.  This causes a crash.  We now check the
tsx state and return if the tsx is already destroyed.

Change-Id: If93acd5e48d9ca5bb553f2405d5afc836842fe1c

third-party/pjproject/patches/0090-sip_transaction-In-tsx_timer_callback-check-if-tsx-i.patch

@@ -0,0 +1,31 @@
+From beaa7874ff8e3b1d2951218c94e7e6bbba9c0531 Mon Sep 17 00:00:00 2001
+From: George Joseph <gjoseph@digium.com>
+Date: Sun, 25 Mar 2018 12:30:05 -0600
+Subject: [PATCH] sip_transaction: In tsx_timer_callback, check if tsx is
+ already gone
+
+There have been cases that when the transaction timer callback is called
+the tsx is already destroyed.  This causes a crash.  We now check the
+tsx state and return if the tsx is already destroyed.
+---
+ pjsip/src/pjsip/sip_transaction.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/pjsip/src/pjsip/sip_transaction.c b/pjsip/src/pjsip/sip_transaction.c
+index d52b12a72..6d4cdc65f 100644
+--- a/pjsip/src/pjsip/sip_transaction.c
++++ b/pjsip/src/pjsip/sip_transaction.c
+@@ -1119,6 +1119,10 @@ static void tsx_timer_callback( pj_timer_heap_t *theap, pj_timer_entry *entry)
+ 
+     PJ_UNUSED_ARG(theap);
+ 
++    if (tsx->state >= PJSIP_TSX_STATE_DESTROYED) {
++        return;
++    }
++
+     if (entry->id == TRANSPORT_ERR_TIMER) {
+ 	/* Posted transport error event */
+ 	entry->id = 0;
+-- 
+2.14.3
+