mpm_event: use apr_atomic_read32() to read queues' ->total instead of volatile access.

* server/mpm/event/event.c (listener_thread): Use apr_atomic_read32() instead
  open coded *(volatile apr_uint32_t*)q->total.

No functional change.

Follow up to r1891716.
Github: #208


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1891718 13f79535-47bb-0310-9956-ffa450edef68
1 file changed