byterange filter: Remove apr 1.3 dependency by

dropping apr_array_clear. The dependency was
introduced by a backport in 2.2.22.

Submitted by: covener
Reviewed by: rjung, trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1445101 13f79535-47bb-0310-9956-ffa450edef68