[llvm] [llvm] Add support for running tests as root (PR #75285)

[Tom Stellard via llvm-commits]

tstellar wrote:

Thanks for the feedback.  I would prefer to keep the patch as-is.  The reason I don't want to use os.getuid() is that it is only available on Unix systems, and I don't want to have to add extra code to do OS detection.  I also don't want to do a specific ACL test, because creating temporary files is adding another point of failure to lit start up.  Since this check is only needed by 4 tests, I want to make it as simple as possible and reduce the risk that it will impact users running as non-root, which is the most common case.

https://github.com/llvm/llvm-project/pull/75285