remove dead code leftover from r1023387.

Prior to this revision, there was an apr_atoi64 in this context.
Now, ap_cache_control() sets control.max_age (which is checked here) when
the maxage value was parsed OK.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1718496 13f79535-47bb-0310-9956-ffa450edef68