Similar to the https://reviews.llvm.org/D86048 (it only sets the bit for C++
code), we propagate the contains-errors bit for C-code path.
Fixes https://github.com/llvm/llvm-project/issues/50236
Fixes https://github.com/llvm/llvm-project/issues/50243
Fixes https://github.com/llvm/llvm-project/issues/48636
Fixes https://github.com/llvm/llvm-project/issues/50320
computeDependence does not feel particularly well organized, it is not clear to me how correct it is :-(