samba4: bump to version 4.2.0

Now with support for AD DC, ADS and clustering features.
All dropped patches are upstream.

[Thomas: move indentation fixes to a separate patch.]

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>