[clang] [clang] Match -isysroot behaviour with system compiler on Darwin (PR #80524)

[Louis Dionne via cfe-commits]

ldionne wrote:

Woah, I just checked Xcode 15.2 and you are totally right, it contains `clang-1500.1.0.2.5` which still has the behavior reversed from upstream. Sorry for the confusion, I assumed it was out in recent Xcodes cause the change was made a while back, but it looks like this change still hasn't made it into a version of Xcode. However, being the author of the change and the one who synced upstream and downstream, I can guarantee you that the upstream behavior is the correct and desired one, I made sure to make it that way. It's just annoying that the downstream hasn't caught up with this change yet, but it's only a matter of time. So IMO, there's unfortunately nothing to do here except wait.

https://github.com/llvm/llvm-project/pull/80524