Caching content from sources where Content-Length is not specified

Caching content from sources where Content-Length is not specified
(these were passed through uncached until now):

This needed additional checks for CacheMinFileSize and CacheMaxFileSize
after the response has completed. That means that we are checking at two
places now:
-> when the C-L is known, we check before we cache
-> when it is unknown we check "on-the-way" for CacheMaxFileSize, and
   after caching completion for CacheMinFileSize

We now compare the actual size of the cached copy against the C-L
header, and discard it if the two don't match.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103026 13f79535-47bb-0310-9956-ffa450edef68