[llvm] [lit] Export env vars in script to avoid pruning (PR #105759)

[Alexander Richardson via llvm-commits]

arichardson wrote:

Just to make sure I understand the problem correctly: on macOS rtld clears these environment variables when we invoking sh/bash to execute the test script?
So my assumption would be that this is not needed for the internal shell, is that correct?

I would like to see this in a comment in the code explaining why we have to export all environment variables. And I'd also prefer if we could just export the ones starting with `DYLD_` to avoid adding extra statements to each test script, slowing down overall execution.

 

https://github.com/llvm/llvm-project/pull/105759