MDEV-11766 Tests failed in buildbot with semaphore waiting warnings
MDEV-11766 Tests failed in buildbot with semaphore waiting warnings

The standalone warning is not a sign of a problem, just of slowness,
so it should be added to global suppressions. If a real problem
happens, there will be other errors

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2