mod_ssl: Fix recognition of OCSP stapling responses that are encoded
         improperly or too large.

The one byte "ok" flag stored with the response was accounted for in
the wrong condition.


follow up to r1641077: 

one bug was traded for another in r1641077; track the response
length and the cached object length separately to avoid such
confusion

Submitted by: trawick
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1645935 13f79535-47bb-0310-9956-ffa450edef68