Follow up to r1821526: mpm_unix.h

The fdqueue code is not for WIN32 (per mpm_unix.c), and does not seem to
require all the #includes (system) it claimed (at least in .h).



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1821527 13f79535-47bb-0310-9956-ffa450edef68