Eliminate last win32-isms, SetLastError becomes apr's set_os_error
  operation.  It unfolds the error code on win32, so we have to pre-fold it.
  On unix there is no folding.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@386821 13f79535-47bb-0310-9956-ffa450edef68