[m-rev.] for review: Defer CPU detection in high-level C grades, and related cleanups.

[Peter Wang]

On Tue, 22 May 2018 18:03:03 +1000, Peter Wang <novalazy at gmail.com> wrote:
> library/thread.m:
>     Make num_processors/3 call a function in the runtime instead of
>     reading a global variable, so we can defer initialisation of the
>     variable.

Committed now so as not to hold up other patches.

Peter