Add cxx_std_ support for write_compiler_detection_header()
Hi, all.
According to the documentation, cxx_std_* features are ignored. But it will be useful to have the support of them due to that the MSVC compilers still have __cplusplus == 199711L. And I have to use
#if __cplusplus > 201402L || _MSC_VER >= 1900
if I want to check if the compiler supports c++17 instead of the single expression.