Merge r617890 from trunk:

* Use a 64 bit unsigned int instead of a signed long to count the bytes
  transferred to avoid integer overflows.

PR: 44346

Submitted by: rpluem
Reviewed by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@649114 13f79535-47bb-0310-9956-ffa450edef68