Adding a MACHINE_ARCH note

[Warner Losh]

On Jul 10, 2013, at 10:41 AM, Adrian Chadd wrote:

> [snip]
> 
> .. boy, wouldn't it be nice to at least check if the package system
> we're about to roll out may support this?
> 
> That's the reason I replied about it. Not specifically to make it
> happen _everywhere_, but to see if we're about to migrate to a tool
> that doesn't support it, making it a much bigger deal to migrate again
> later.

I've been talking to Baptiste, and it will support this.

Warner