Explicit conversion to 'long' of curl_easy_setopt() third argument for options
CURLOPT_HTTPAUTH and CURLOPT_PROXYAUTH given that this is how its bitmasks are
docummented to be used.
This test is created to verify Rene Bernhardt's patch which makes sure
libcurl properly _not_ deals with Negotiate if not asked to even if the
proxy says it can serve it.