mpm_fdqueue: return EOF for ap_queue_interrupt_*() when terminated.

* server/mpm_fdqueue.c (queue_interrupt): noop and return APR_EOF when queue is
  terminated already.

* server/mpm_fdqueue.h (struct fd_queue_t): make "terminated" volatile.

Follow up to r1891716.
Github: closes #208


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1891724 13f79535-47bb-0310-9956-ffa450edef68
2 files changed