Description:
------------
Under the apache2handler SAPI, setting a Content-Length header via header() with a value beyond LONG_MAX will result in the value being truncated to LONG_MAX, even when the apr_off_t type allows for a larger value, due to the unconditional use of strtol() in php_apache_sapi_header_handler() on non-Windows platforms.

To fix this, we should check sizeof(apr_off_t) and call strtoll() as appropriate.

Test script:
---------------
<?php
header('Content-Length: 4294967296');
header('Content-Type: application/octet-stream');
$fp = fopen('/dev/zero', 'rb');
fpassthru($fp);
fclose($fp);
?>

Place in an Apache 2 handler environment, and then use curl -I to send a HEAD request and get the headers.

Expected result:
----------------
HTTP/1.1 200 OK
Date: Sun, 08 Nov 2015 14:11:19 GMT
Server: Apache/2.4.7 (Ubuntu) PHP/5.6.16-dev
X-Powered-By: PHP/5.6.16-dev
Content-Length: 4294967296
Content-Type: application/octet-stream

Actual result:
--------------
HTTP/1.1 200 OK
Date: Sun, 08 Nov 2015 14:03:35 GMT
Server: Apache/2.4.7 (Ubuntu) PHP/5.6.16-dev
X-Powered-By: PHP/5.6.16-dev
Content-Length: 2147483647
Content-Type: application/octet-stream