Port Justin's mod_cgid change to mod_cgi.

mod_cgi wasn't actually broken in the way that mod_cgid was, but
it's still good do have these checks be against APR_SUCCESS rather
than 0 for clarity.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91868 13f79535-47bb-0310-9956-ffa450edef68