ClientBuilder fixes for PHP 5.4

Upstream GuzzleHttp\Ring\Client\CurlHandler (dubiously) requires `curl_reset` available from PHP 5.5, so when using `ClientBuilder::singleHandler() directly`, the check for `curl_reset` should take place or throw the Exception. `ClientBuilder::defaultHandler()` should also perform this check, falling back to Upstream GuzzleHttp\Ring\Client\CurlMultiHandler in environments where `curl_reset` is not available (the multi handler has no such dependency on curl_reset)

The ClientBuilder::multiHandler() method doesn't require `curl_reset`, but does require `curl_multi_init`, which should be available to those with the curl extention.

Author: simplechris

src/Elasticsearch/ClientBuilder.php

@@ -95,7 +95,7 @@ public static function defaultHandler($multiParams = [], $singleParams = [])
         $future = null;
         if (extension_loaded('curl')) {
             $config = array_merge([ 'mh' => curl_multi_init() ], $multiParams);
-            if (function_exists('curl_multi_init')) {
+            if (function_exists('curl_reset')) {
                 $default = new CurlHandler($singleParams);
                 $future = new CurlMultiHandler($config);
             } else {
@@ -127,7 +127,7 @@ public static function multiHandler($params = [])
      */
     public static function singleHandler()
     {
-        if (function_exists('curl_multi_init')) {
+        if (function_exists('curl_reset')) {
             return new CurlHandler();
         } else {
             throw new \RuntimeException('CurlSingle handler requires cURL.');