[compiler-rt] [TySan] Fix struct access with different bases (PR #120412)

[Sean McBride via llvm-commits]

seanm wrote:

@gbMattN thanks! I've got the patch locally and built a working clang. Running the test suite of a project I'm testing, with your patch, I went from 827 occurrences of "ERROR: TypeSanitizer" down to... 827. :(  So I guess my issue is something else...

https://github.com/llvm/llvm-project/pull/120412