/*
 * call-seq:
 *   easy.proxy_auth_types = fixnum or nil            => fixnum or nil
 *
 * Set the proxy authentication types that may be used for the following
 * +perform+ calls. This is a bitmap made by ORing together the
 * Curl::CURLAUTH constants.
 */
static VALUE ruby_curl_easy_proxy_auth_types_set(VALUE self, VALUE proxy_auth_types) {