[llvm] [mlir] [CMake] Do not set CMP0116 explicitly to old (PR #90385)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> @boomanaiden154 Looks like the real issue.
https://gitlab.kitware.com/cmake/cmake/-/issues/25943

That definitely seems like the culprit. Thanks for finding that!

> Could you tri other versions of CMake?

Theoretically yes, but it would be difficult to update the precommit CI. That fix only landed in CMake 3.30, which means that other Windows users could run into the same issue, especially since our CMake requirements are quite a ways behind where the patch laneded.

It seems like a reasonable path forward might be to force the new behavior on Linux, but keep the old behavior on Windows in these two specific spots, with a note that we should switch later remove this workaround once we require CMake 3.30 or later. That gets rid of the warning on Linux, prevents us from accidentally depending on the behavior in the future, and keeps things working completely on Windows. Thoughts?

https://github.com/llvm/llvm-project/pull/90385