MINOR Defined $column as an array so "undefined variable" error is supressed

git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/branches/2.3@70132 467b73ca-7a2a-4603-9d3b-597d59a354a9

core/model/Database.php

@@ -546,6 +546,7 @@ abstract class Query extends Object implements Iterator {
 	 * @return array
 	 */
 	public function map() {
+		$column = array();
 		foreach($this as $record) {
 			$key = reset($record);
 			$val = next($record);