Add a new LogFormat directive, %c, that will log connection

status at the end of the response as follows:
'X' - connection aborted before the response completed.
'+' - connection may be kept-alive by the server.
'-' - connection will be closed by the server.

Doc. update will be committed RSN...


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@86810 13f79535-47bb-0310-9956-ffa450edef68