This tracks all the compiler/llvm changes needed for building Fuchsia with the HWASan variant.
Nit: can you move this above TSan so it's alphabetically sorted?
Can you move this above relative-vtables so we keep all sanitizers together?
I don't think this applies to Fuchsia.
It might be better to move this function to a per-platform file rather than conditionally compiling the entire body.