[compiler-rt] [Sanitizers][Darwin] Pass offset to __asan_set_shadow_xx (PR #71745)

[Roy Sundahl via llvm-commits]

rsundahl wrote:

cc: @kcc and @vitalybuka... (I don't think that it's ideal that the instrumentation is really even _aware_ of the shadow memory when -fsanitize-stable-abi in the sense that the implementation of the stable ABI would preferably be implementation agnostic but that's a bigger lift than I think we can make atm.)

https://github.com/llvm/llvm-project/pull/71745