Merge r1617913 from trunk:

* support/ab.c: Fix crash caused by integer overflow when printing stats with
lot of requests (for example -n 500000000).

Submitted by: jkaluza
Reviewed by: jorton, jim, ylavic


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1826310 13f79535-47bb-0310-9956-ffa450edef68