Support TCP_NODELAY for stream-based connections on PHP >= 5.4.0.

This cannot be implemented for previous versions of PHP because we
need socket_import_stream() to extract the underlying socket resource
from the stream in order to be able to set the TCP_NODELAY flag.

lib/Predis/Connection/StreamConnection.php

@@ -101,6 +101,11 @@ class StreamConnection extends AbstractConnection
             stream_set_timeout($resource, $timeoutSeconds, $timeoutUSeconds);
         }
 
+        if (isset($parameters->tcp_nodelay) && version_compare(PHP_VERSION, '5.4.0', '>=')) {
+            $socket = socket_import_stream($resource);
+            socket_set_option($socket, SOL_TCP, TCP_NODELAY, (int) $parameters->tcp_nodelay);
+        }
+
         return $resource;
     }