res_pjsip_outbound_authenticator_digest: Prevent ABRT on cleanup

In dev mode, if you call pjsip_auth_clt_deinit() with an auth_sess
that hasn't been initialized, it'll assert and abort.  If
digest_create_request_with_auth() fails to find the proper
auth object however, it jumps to its cleanup which does exactly
that.  So now we no longer attempt to call pjsip_auth_clt_deinit()
if we never actually initialized it.

ASTERISK-29888

Change-Id: Ib6171c25c9fe8e61cc8d11129e324c021bc30b62

res/res_pjsip_outbound_authenticator_digest.c

@@ -560,8 +560,10 @@ static int digest_create_request_with_auth(const struct ast_sip_auth_vector *aut
 
 cleanup:
 #if defined(HAVE_PJSIP_AUTH_CLT_DEINIT)
-	/* Release any cached auths */
-	pjsip_auth_clt_deinit(&auth_sess);
+	/* If we initialized the auth_sess, clean it up */
+	if (auth_sess.endpt) {
+		pjsip_auth_clt_deinit(&auth_sess);
+	}
 #endif
 
 	ast_sip_cleanup_auth_objects_vector(&auth_objects_vector);