Scott Cantor filed bug report #1766320

(http://curl.haxx.se/bug/view.cgi?id=1766320) pointing out that the libcurl
code accessed two curl_easy_setopt() options (CURLOPT_DNS_CACHE_TIMEOUT and
CURLOPT_DNS_USE_GLOBAL_CACHE) as ints even though they're documented to be
passed in as longs, and that makes a difference on 64 bit architectures.