ipa-extdom-extop: Update licenses to GPLv3 or later with exceptions
    
    The code in question was supposed to have the same license as the
    rest of the plugin. Fix it by updating the comment header.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Thomas Woerner <twoerner@redhat.com>