[CMake] Disable mvsc warning for new versions

Starting with VS 2019, CMake defaults to the x64 host toolchain, so the
warning does not apply anymore.

References:
VS 2017 defaults to x86
https://cmake.org/cmake/help/latest/generator/Visual%20Studio%2015%202017.html?highlight=host#toolset-selection
VS 2019 and 2022 default to x64 for x64 targets
https://cmake.org/cmake/help/latest/generator/Visual%20Studio%2016%202019.html?highlight=host#toolset-selection
https://cmake.org/cmake/help/latest/generator/Visual%20Studio%2017%202022.html?highlight=host#toolset-selection

Differential Revision: https://reviews.llvm.org/D118228