Change _only_ the debug build to recognize the /Zi flag (which is portable
  for debugging between VC 5.0/6.0/7.0) instead of the VC 6.0+ specific /ZI.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90675 13f79535-47bb-0310-9956-ffa450edef68