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

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Last I checked, setting this to new causes issues with cmake consuming TableGens dep files. I don't fully remember the sympton but I think it'd either claim that a TableGen command is always out of date or it would not capture all dependencies and therefore not rereun a TableGen command if an included file changed.
>
> There was a PR that would address this here https://github.com/llvm/llvm-project/pull/72333. Is this still needed/the case?

Looks like it's still needed. I didn't realize this was an issue. Thanks for bringing this up! I'll make sure that gets fixed before we merge this/merge this as part of the fix.

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