Add backport proposal for MaxRanges configuration

directive and ap_set_accept_ranges() utility function.

With that 2.0.x should be on par with 2.2.x w.r.t.
Ranges.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@1177239 13f79535-47bb-0310-9956-ffa450edef68