Import the core parts of the DTrace patch. This is a modified and updated

Import the core parts of the DTrace patch.  This is a modified and updated
version of what was submited by Theo before:
 <http://mail-archives.apache.org/mod_mbox/httpd-dev/200805.mbox/%3C6AFBCFE8-4CCA-4A02-8A43-F9170689695D@omniti.com%3E>

Note, this does not hook it up into the build system at this time, because
the original patch was a little too creative there.

Submitted By: Theo Schlossnagle <jesus omniti.com>

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@723565 13f79535-47bb-0310-9956-ffa450edef68