mod_disk_cache: Remove the directory path of the cached file as far as possible

(up to the cache root) to get rid of unused empty directories.

* cache/mod_disk_cache.c
  (remove_url): Try to delete directories; also change two APR_ENOENT to
  APR_STATUS_IS_ENOENT.

(Justin tweaked some comments.)

Submitted by: Rudiger Plum <ruediger.pluem vodafone.com>
Reviewed by: Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@232334 13f79535-47bb-0310-9956-ffa450edef68