Backport r1175980, r1175992:

    byterange: Range of '0-' returns 206

Submitted by: Jim Jagielski
Reviewed by: jim, rpluem, rjung, sf


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1177080 13f79535-47bb-0310-9956-ffa450edef68