Merge branch '2753-timer_test-subtests-are-not-independent-v9_16' into 'v9_16'

Reset errcnt at the start of each subtest

See merge request isc-projects/bind9!5258

lib/isc/tests/timer_test.c

@@ -114,6 +114,8 @@ setup_test(isc_timertype_t timertype, isc_time_t *expires,
 
 	isc_condition_init(&cv);
 
+	atomic_store(&errcnt, ISC_R_SUCCESS);
+
 	LOCK(&mx);
 
 	result = isc_task_create(taskmgr, 0, &task);