[TSan] Add CMake check for minimal SDK requirements on Darwin

Fails with the following message in the error case:
```
CMake Error at /path/to/llvm-project/compiler-rt/lib/tsan/CMakeLists.txt:119 (message):
  Building the TSan runtime requires at least macOS SDK 10.12
```

Fixes #44682.
https://bugs.llvm.org/show_bug.cgi?id=44682

Reviewed By: dmajor, delcypher

Differential Revision: https://reviews.llvm.org/D74501