Make sure we write a reasonable status line (e.g., if byterange

filter modifies status and custom status line is left
unmodified).

Reviewed by: niq, gregames


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@393008 13f79535-47bb-0310-9956-ffa450edef68