Backport r657433 by rpluem

* Include <limits.h> earlier if available since INT_MAX is defined there on
  Windows and we need INT_MAX already for the definition of MAX_REQUESTS.

PR: 45024


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@660702 13f79535-47bb-0310-9956-ffa450edef68