sipsess: do not call desc handler on shutdown
This fixes a segfault that occurs when the session is terminated abnormally.
@@ -66,6 +66,7 @@ static bool termwait(struct sipsess *sess)
bool wait = false;
sess->terminated = 1;
+ sess->desch = NULL;
sess->offerh = internal_offer_handler;
sess->answerh = internal_answer_handler;
sess->progrh = internal_progress_handler;
