Fix QB delete() for multiple tables with where()

Reported via the forums: http://forum.codeigniter.com/thread-61774.html
diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 859f9f5..a8b5b35 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -2092,10 +2092,13 @@
 		}
 		elseif (is_array($table))
 		{
+			empty($where) && $reset_data = FALSE;
+
 			foreach ($table as $single_table)
 			{
 				$this->delete($single_table, $where, $limit, $reset_data);
 			}
+
 			return;
 		}
 		else