Use APR_STATUS_IS_TIMEUP instead of direct compare to APR_TIMEUP to

      be more safe on different platforms.

Note: This commit has an additional, platform-independent change to
mark the back-end connection for closing ("backend->close = 1;").
That code is not required to resolve CVE-2010-2068 on any platform.

PR: 49417
Addresses CVE-2010-2068


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@953418 13f79535-47bb-0310-9956-ffa450edef68