siprec: send BYE for sessions not established

When a SIPREC session was started on a 183 reply, but the session was
not stopped, a BYE to the SIPREC server should be sent to close the
session.

Thanks go to Krunal Patel for reporting this and offering the fix.

Close #2136

(cherry picked from commit b4cd132)

modules/siprec/siprec_logic.c

@@ -172,7 +172,7 @@ static void srec_dlg_sequential(struct dlg_cell *dlg, int type, struct dlg_cb_pa
 int srec_register_callbacks(struct src_sess *sess)
 {
 	/* also, the b2b ref moves on the dialog */
-	if (srec_dlg.register_dlgcb(sess->dlg, DLGCB_TERMINATED|DLGCB_EXPIRED,
+	if (srec_dlg.register_dlgcb(sess->dlg, DLGCB_TERMINATED|DLGCB_EXPIRED|DLGCB_FAILED,
 			srec_dlg_end, sess, src_unref_session)){
 		LM_ERR("cannot register callback for dialog termination\n");
 		return -1;