mod_cache: use the correct struct for CacheDisable.

Currently any use of CacheDisable disables all caching.
PR:	31128
Obtained from:
Submitted by:	Edward Rudd <eddie omegaware.com>, Paul Querna
Reviewed by:	pquerna, stoddard, jerenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@105559 13f79535-47bb-0310-9956-ffa450edef68