[CMake] Disable mvsc warning for new versions

[sebastian-ne]

Summary

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

[aaron.ballman]

LGTM!

llvm/CMakeLists.txt

if(NOT DEFINED LLVM_VERSION_SUFFIX)
   set(LLVM_VERSION_SUFFIX git)
 endif()
 
 if (NOT PACKAGE_VERSION)
   set(PACKAGE_VERSION
     "${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}${LLVM_VERSION_SUFFIX}")
 endif()
 
-if ((CMAKE_GENERATOR MATCHES "Visual Studio") AND (CMAKE_GENERATOR_TOOLSET STREQUAL ""))
+if ((CMAKE_GENERATOR MATCHES "Visual Studio") AND (MSVC_TOOLSET_VERSION LESS 142) AND (CMAKE_GENERATOR_TOOLSET STREQUAL ""))
   message(WARNING "Visual Studio generators use the x86 host compiler by "
                   "default, even for 64-bit targets. This can result in linker "
                   "instability and out of memory errors. To use the 64-bit "
                   "host compiler, pass -Thost=x64 on the CMake command line.")
 endif()
 
 if (CMAKE_GENERATOR STREQUAL "Xcode" AND NOT CMAKE_OSX_ARCHITECTURES)
   # Some CMake features like object libraries get confused if you don't