[PATCH] Enable MISched on AArch64

[Tim Northover]

Hi Kristof,

> Were you planning on running only the regression tests or also the
> full test suite?

Just the regression tests, under a self-hosted Clang (obviously). The
full test-suite takes 29 hours and gives noisy results even after that
(various spurious failures, as I recall).

That said, I'd be happy to wait for you to do a test suite run if you
want. My main purpose here is to unblock Hao's work; I'm not dependent
on it happening quickly.

Cheers.

Tim.