mod_cache_socache: Fix warning "variable 'rv' may

be used uninitialized in this function"
(which is correct here).

Backport of r1494536 form trunk.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1494597 13f79535-47bb-0310-9956-ffa450edef68