Define empty array as []
    
    This is recommended by jshint: they are identical in terms of
    functionality, but the square brackets are more commonly used and thus
    more readable.
    
    Merges https://pagure.io/pagure/pull-request/3033
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>