Is the build version still a 64 bit version and :WIN32 is added by error?
Is the variable ECL_WIN64 just ignored?
This feature is related to the OS API that is used Win32 vs Mingw32 vs Cygwin32. On Windows64 the API used is still Win32, IIRC. I do not know how to change this without breaking some code out there, or whether the present situation is sensible or not. Maybe we coud at least push also Win64