This patch fixes several problems with mod_file_cache

- Pool usage problem
- SIGSEGVs when both MMapFile and CacheFile directives are present.  The fix combines
the cleanup routines and only cleans up resources when appropriate.
- Log sendfile errors.

Submitted by:	Greg Ames
Reviewed by:	Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85781 13f79535-47bb-0310-9956-ffa450edef68