XFAIL status-listen FPM test

Has frequent intermittent failures with:

ERROR: The NOTICE does not match expected message:
- PATTERN: /^\[\d\d-\w\w\w-\d{4} \d\d:\d\d:\d\d\] NOTICE: Terminating ...$/
- MESSAGE: [04-Aug-2020 08:15:37] WARNING: [pool unconfined_status] server reached max_children setting (2), consider raising it
- EXPECT: 'Terminating ...'
- ACTUAL: '2020 08:15:37] WARNING: [pool unconfined_status] server reached max_children setting (2), consider raising it'

Author: nikic

sapi/fpm/tests/status-listen.phpt

@@ -2,6 +2,8 @@
 FPM: Status listen test
 --SKIPIF--
 <?php include "skipif.inc"; ?>
+--XFAIL--
+Flaky test
 --FILE--
 <?php