content with "Content-Encoding" header, content is encoded.
But mod_deflate does not check it. It cause to encode content twice.

This problem is reproducable by getting encoded content via mod_proxy.

Patch Contributed by kaz@asada.sytes.net (ASADA Kazuhisa)
Bug #9222

Thanks Kazuhisa


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95181 13f79535-47bb-0310-9956-ffa450edef68