FYI: MLIR is now part of LLVM repo

[Johan Engelen]

Hi all,
   MLIR landed in the LLVM project repository today: 
https://github.com/llvm/llvm-project/tree/master/mlir

You can enable it by:
  `cmake -DLLVM_ENABLE_PROJECTS="mlir" ......`

cheers,
   Johan