Remove executable permission bits from ctdb service file
    
    Avoids the following warning message from /var/log/messages:
    
    ...
    systemd: Configuration file /usr/lib/systemd/system/ctdb.service
    is marked executable. Please remove executable permission bits.
    Proceeding anyway.
    ...
    
    Signed-off-by: Anoop C S <anoopcs@redhat.com>