mod_deflate:

- fix signed/unsigned (int/size_t) comparisons,
- add consume_buffer() to factorize code used multiple times,
- cleanup passed brigade (don't rely on next output filters to do it).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1619486 13f79535-47bb-0310-9956-ffa450edef68