Fix mod_deflate corruption when using multiple input buckets. We should

only clear *_out when we are the beginning or avail_out == 0.

Justin was tracking this down before he went to WWDC and didn't finish
before he left.  A (virtual) beer goes to Asada who filed this PR with
the right patch!

PR: 9014
Submitted by:	kaz@asada.sytes.net (ASADA Kazuhisa)
Reviewed by:	Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95055 13f79535-47bb-0310-9956-ffa450edef68