* Fix wrong FLUSH bucket handling in deflate_out_filter: Actually the internal

  structures of libz never got flushed as ctx->stream.avail_in is always zero
  here. As the EOS and the FLUSH bucket case use the same code for flushing
  libz's internal buffers move this code to the new function flush_zlib_buffer.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@422731 13f79535-47bb-0310-9956-ffa450edef68