Add casts for systems where sizeof(off_t) > sizeof(long).

Sorry, but I see no other portable way to do it :-(
Submitted by:	Ralf Engelschall <rse@engelschall.com>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81526 13f79535-47bb-0310-9956-ffa450edef68