Realign the cache_quick_handler() and cache_handler() to behave identically

to the default_handler() when it comes to reacting to errors when writing
to the filter stack. Previously the error message implied the cache had
failed, when in reality, any part of the filter stack may have returned an
error.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1003913 13f79535-47bb-0310-9956-ffa450edef68