[PATCH] ARM64: start porting regression tests from AArch64

[Tim Northover]

> Shouldn't changing 'or' to 'and' in lit config just work? I think you just
> want to say we need to run the test under AArch64 for both AArch64 and
> ARM64, right?

It needs both, unfortunately. llvm-lit has no way to know which RUN
lines need ARM64 and which need AArch64, so it needs all of them to
succeed.

Cheers.

Tim.