s4:selftest: run the nbt tests before the smb tests

s4:selftest: run the nbt tests before the smb tests

This hopefully avoids to run into problems with the
flakey error in the samba4.nbt.winsreplication test

 [1071/1154 in 58m58s] samba4.nbt.winsreplication(dc)
 Test if we always get back the same assoc_ctx
 Setup wrepl connections
 Test one pull replication cycle
 Setup wrepl connections
 Setup wrepl conflict pull connection
 UNEXPECTED(error): samba4.nbt.winsreplication.replica
 REASON: _StringException: _StringException: Unknown error/failure

metze

Autobuild-User: Stefan Metzmacher <metze@samba.org>
Autobuild-Date: Mon Sep 19 16:29:22 CEST 2011 on sn-devel-104