Correctly store cache content type.

PR:	30278
Obtained from:
Submitted by:	[R��iger Pl�� <r.pluem t-online.de>]
Reviewed by:	stoddard, jerenkrantz, minfrin, jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@105429 13f79535-47bb-0310-9956-ffa450edef68