This time from the top, with three part harmony AND feeling...

Revert the read-while-caching and large-file-crash fixes for mod_disk_cache,
ready to start again.

Reverted: r450105 r450188 r462571 r462601 r462696 r467655 r467684 r468044
r468373 r468409 r470455



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@502365 13f79535-47bb-0310-9956-ffa450edef68