TODO: auth: For NTLM and KDC authentication, log the authentication duration

TODO: auth: For NTLM and KDC authentication, log the authentication duration

This is not a general purpose profiling solution, but these JSON logs are already being
generated and stored, so this is worth adding.

Some administrators are very keen to know how long authentication
takes, particularly due to long replication transactions in other
processes.

This complements a similar patch set to log the transaction duration.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
(Simlar to Samba commit 1bb2a1c6b3eaccf114ac3f3b5b51f57828a04996)
[metze@samba.org: improved for upstream heimdal]
Signed-off-by: Stefan Metzmacher <metze@samba.org>