Detect APR_EINTR from ap_queue_pop() and avoid calling

ap_queue_info_set_idle() more than once at a time per worker thread.
This fixes an assert coredump.

Submitted by:	Aaron Bannert
Reviewed by:	Brian Pane


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@94840 13f79535-47bb-0310-9956-ffa450edef68