After getting confirmation from Guenther, add 3 changes we'll ultimately need to...

After getting confirmation from Guenther, add 3 changes we'll ultimately need to fix bug #6099 Samba returns incurrate capabilities list. 1). Add a comment to point out that r->in.negotiate_flags is an aliased pointer to r->out.negotiate_flags. 2). Ensure we return NETLOGON_NEG_STRONG_KEYS in our flags return if the client requested it. 3). Clean up the error exits so we always return the same way. Signed off by Guenther. Jeremy.
(cherry picked from commit 59ee131464636d3363bc7ee398ba6390a6333558)