5.4 not running HTT

[Colin Percival]

Erik Trulsson wrote:
> It depends on which version you are looking at the source of. 
> In the release/security branches (RELENG_5_4, etc.) all security
> patches (like this one) are noted in UPDATING.  For the development
> branches (RELENG_5 , -CURRENT) security patches usually don't get
> mentioned.
> 
> I.e. if you are looking at the source for RELENG_5_4 there is a notice
> in UPDATING, if you are looking at the source for RELENG_5 there is
> not.  In this particular case there probably should have been a note
> added to UPDATING for both -STABLE and -CURRENT, but there wasn't.

Quite right -- we fell into the trap of just following our standard
procedures, instead of thinking about whether this met the test for
being documented in UPDATING (which it certainly does, since it is a
potentially astonishing user-visible change).

I've added it to the stable branches, but not to -current, since
hyper-threading is still enabled by default in HEAD.

Colin Percival