patches to make bind9 with TKEY/GSS updates easier to configure

[tridge at samba.org]

Hi Evan,

 > Without having reviewed the patch, two comments:
 > 
 >  - should this be a named.conf option instead of an environment variable?

You mean like tkey-domain? The problem with that is that users may
well want to do updates in multiple realms. What would they put in
named.conf to support that?

Also, the named.conf should configure the local named, whereas this
code is for nsupdate, which can be used against any DNS server on the
network. The local named.conf may not match the server you are
updating.

 >  - can this be used in the tsiggss test, so that the test can run without
 >    need for any system-wide configuration?

we can use it to get rid of this line in bin/tests/system/tsiggss/tests.sh:

 export KRB5_CONFIG=$(pwd)/ns1/krb5.conf

I've pushed a patch to my repo that does that.

Cheers, Tridge