Merge r657933 from trunk:

* Only send 100-continue if the status code so far indicates success.

PR: 43711

Submitted by: rpluem
Reviewed by: rpluem, niq, trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@660569 13f79535-47bb-0310-9956-ffa450edef68