Move _() to compat.php

git-svn-id: https://develop.svn.wordpress.org/trunk@3901 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/compat.php

@@ -111,4 +111,11 @@ if(!function_exists('http_build_query')) {
        return implode($separator, $res);
    }
 }
+
+if ( !function_exists('_') ) {
+	function _($string) {
+		return $string;
+	}
+}
+
 ?>