add check if mysql module is configured but not installed. This is catching people who upgrade to PHP7

modules/gallery/libraries/MY_Database_Mysql.php

@@ -0,0 +1,35 @@
+<?php defined("SYSPATH") or die("No direct script access.");
+/**
+ * Gallery - a web based photo album viewer and editor
+ * Copyright (C) 2000-2013 Bharat Mediratta
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+class Database_Mysql extends Database_Mysql_Core {
+
+	public function connect()
+	{
+		if ($this->connection)
+			return;
+
+		if (!function_exists('mysql_connect')) {
+			$msg = 'You configured your DB to use the "mysql" module but the PHP mysql module doesn\'t appear to be installed. If you are upgrading to PHP 7 you should update var/database.php to use the mysqli module instead of mysql.';
+			print $msg;
+			throw new Kohana_Exception($msg);
+		}
+
+		return parent::connect();
+	}
+}