Unlike direct tests of __cplusplus, using this macro also works with (recent enough, i.e. MSVS 2015.3 or later) MSVC versions, even if /Zc:__cplusplus is not used. This simplifies some checks and makes some other ones (notably the check for C++20 used before wxALLOW_COMBINING_ENUMS macro definition) work with MSVC versions with C++20 support as intended.