[compiler-rt] [compiler-rt] [Darwin] Strip MTE tags from ASAN and TSAN (PR #166453)

[Dan Blackwell via llvm-commits]

DanBlackwell wrote:

> > >ASAN and TSAN need to strip tags in order to compute the correct shadow addresses.
> >
> > What is the point of running Asan with MTE?
>
> Also Tsan has its own allocator, which does not tag.

Other linked (uninstrumented) libraries can use their own MTE-backed allocator, but Asan / Tsan will still intercept their calls and then `IsAddrInMem` and friends could misclassify them (due to the tag making it appear to be an ultra-high address).

https://github.com/llvm/llvm-project/pull/166453