MSVC / Windows confusion

[diorcety]

Here https://github.com/zeromq/zproject/blob/master/zproject_cmake.gsl#L281
It said that it is specific to Windows, but the if is related to MSVC.
The if is not correct it should be WIN32, because the issue also append with gcc or clang (using msys2 for example)
Which I'm confirm, the sources are not compiled with CZMQ_EXPORTS and DLL_EXPORT, so at the end the dll can't be created.

[sphaero]

Is this still relevant? The line says:

for class where draft
.       if project.use_cxx