Merge r1801143 from trunk:

mpm_winnt: Don't forget to close the I/O completion port as part of the
cleanup in the child process.

Submitted by: kotkov
Reviewed by: jailletc36, ylavic (by inspection), covener


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1838102 13f79535-47bb-0310-9956-ffa450edef68