Port number the proxy listens on
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXYPORT, long port);
Pass a long with this option to set the proxy port to connect to unless it is specified in the proxy string CURLOPT_PROXY(3) or uses the default one.
While this accepts a 'long', the port number is 16 bit so it can't be larger than 65535.
0, not specified which makes it use the default port
All
TODO
Always
Returns CURLE_OK