[Pkg-samba-maint] Bug#726459: MIT instead of Heimdal in Debian

[Mathieu Parent]

Hi,

Most of this was done in Samba 4.8, but we still build with Heimdal in Debian.

There are two reasons:
- missing features [1]
- fear to break things (especially on upgrade)

I hope that the feature gap will decrease in 4.9 and later, but we
probably won't migrate before buster+1 (i.e next-next stable)

Regards

-- 
Mathieu Parent

[1]: Samba DCs with MIT Kerberos KDC currently do not support:
- PKINIT support required for using smart cards
- Service for User to Self-service (S4U2self)
- Service for User to Proxy (S4U2proxy)
- Running as a Read only domain controller (RODC)
(https://wiki.samba.org/index.php/Running_a_Samba_AD_DC_with_MIT_Kerberos_KDC)