PCH: #pragma system_header in generated cmake_pch.hxx leads to warning 4068 with MSVC
When using MSVC with target_precompile_headers
there is the case that leads to compile error:
/W4 /WX.
Warning 4068 is throwing always from generated cmake_pch.hxx.
Solution: Do not write this unknown pragma to generated file if MSVC is used.
I'm using MSVC 14.12 and CMake 3.16.6