[llvm-dev] Clang-12 fails build on MacOS

[Raul Tambre via llvm-dev]

Thanks for the info, however I don't think we still understand the root cause. 
Why do we end up with two instances trying to create the symlink to the same 
location?

Per my thinking different targets end up with separate build directories thus 
this shouldn't happen. And since the different runtime builds are sub-builds 
your proposed dependency tracking solution wouldn't work.