Some minimal tweaks to mod_cache.

* modules/cache/mod_mem_cache.c

  (store_headers): Remove unused variable.


* modules/cache/mod_cache.c

  (cache_save_filter): Slightly improve comment.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@153104 13f79535-47bb-0310-9956-ffa450edef68