Implements hook_install().
function block_install() {
// Block should go first so that other modules can alter its output
// during hook_page_alter(). Almost everything on the page is a block,
// so before block module runs, there will not be much to alter.
db_update('system')
->fields(array(
'weight' => -5,
))
->condition('name', 'block')
->execute();
}