Use apr_off_t for the content length, rather than long. Propagate through

the byterange handling and ap_set_content_length().

[ ap_each_byterange() remains as an apr_size_t* so we don't mess up callers ]


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86860 13f79535-47bb-0310-9956-ffa450edef68