Merge pull request #280 from nickygerritsen/master

Use call_user_func, as this will work on PHP < 5.4, whereas $callback() does not

* nickygerritsen/master:
  Also replace this with call_user_func
  Use call_user_func, as this will work on PHP < 5.4, whereas $callback() does not

phpseclib/Net/SCP.php

@@ -216,7 +216,7 @@ class Net_SCP
             $sent+= strlen($temp);
 
             if (is_callable($callback)) {
-                $callback($sent);
+                call_user_func($callback, $sent);
             }
         }
         $this->_close();

phpseclib/Net/SSH2.php

@@ -2258,7 +2258,7 @@ class Net_SSH2
                     return false;
                 default:
                     if (is_callable($callback)) {
-                        $callback($temp);
+                        call_user_func($callback, $temp);
                     } else {
                         $output.= $temp;
                     }