Disable cmake macros (#5021)
* Disable cmake macros
When building pytorchxla, we need to inform pytorch headers that we're not using CMake.
https://github.com/pytorch/pytorch/blob/5ac48eb353247e86684bfafa8e371eccd17951d7/c10/macros/Macros.h#L11-L19
* Update BUILD
Fix typo.
