Description:
------------
cURL has supported download an upload rate limiting via CURLOPT_MAX_RECV_SPEED_LARGE and CURLOPT_MAX_SEND_SPEED_LARGE for some time.  Support for these options needs to be added to ext/curl/interface.c (they are simple integer values so no special support is needed, they just need to be added to the constant definitions and switch statement).

Test script:
---------------
<?php

// create a new cURL resource
$ch = curl_init();

$fh = fopen("out.dat", "w");

// set URL and other appropriate options
curl_setopt($ch, CURLOPT_MAX_RECV_SPEED_LARGE, 10240);
curl_setopt($ch, CURLOPT_URL, "http://bitcast-a.bitgravity.com/bitgravity/1MB");
curl_setopt($ch, CURLOPT_FILE, $fh);
curl_setopt($ch, CURLOPT_HEADER, 0);

// grab URL
curl_exec($ch);

// close cURL resource, and free up system resources
curl_close($ch);
fclose($fh);
?>


Expected result:
----------------
Script should take at least 100 seconds to run (no matter the speed of the local internet connection).

Actual result:
--------------
Currently, because CURLOPT_MAX_RECV_SPEED_LARGE is not implemented in the cURL extension, the script takes as long as downloading the file over the local internet connection takes, i.e. there is no rate limiting.