CRM-13879 - Strict warning

http://issues.civicrm.org/jira/browse/CRM-13879

CRM/Export/BAO/Export.php

@@ -1136,7 +1136,7 @@ INSERT INTO {$componentTable} SELECT distinct gc.contact_id FROM civicrm_group_c
    * Function to handle import error file creation.
    *
    */
-  function invoke() {
+  static function invoke() {
     $type = CRM_Utils_Request::retrieve('type', 'Positive', CRM_Core_DAO::$_nullObject);
     $parserName = CRM_Utils_Request::retrieve('parser', 'String', CRM_Core_DAO::$_nullObject);
     if (empty($parserName) || empty($type)) {
@@ -1173,7 +1173,7 @@ INSERT INTO {$componentTable} SELECT distinct gc.contact_id FROM civicrm_group_c
     CRM_Utils_System::civiExit();
   }
 
-  function exportCustom($customSearchClass, $formValues, $order) {
+  static function exportCustom($customSearchClass, $formValues, $order) {
     $ext = CRM_Extension_System::singleton()->getMapper();
     if (!$ext->isExtensionClass($customSearchClass)) {
       require_once (str_replace('_', DIRECTORY_SEPARATOR, $customSearchClass) . '.php');
@@ -1813,7 +1813,7 @@ LIMIT $offset, $limit
    * or have no street address
    *
    */
-  function postalMailingFormat($exportTempTable, &$headerRows, &$sqlColumns, $exportParams) {
+  static function postalMailingFormat($exportTempTable, &$headerRows, &$sqlColumns, $exportParams) {
     $whereClause = array();
 
     if (array_key_exists('is_deceased', $sqlColumns)) {