mod_reqtimeout: Don't let pipelining checks and keep-alive times interfere

with the timeouts computed for subsequent requests.  PR 56729.

Submitted by: covener, ylavic
Backports: 1621453, 1641376, 1689325
Reviewed by: ylavic, wrowe, covener



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1689922 13f79535-47bb-0310-9956-ffa450edef68