WINAPI_FAMILY_PARTITION macros are not available

[ccawley2011]

Recent versions of the Windows SDK contain the winapifamily.h header, which defines WINAPI_FAMILY_PARTITION and related macros which are used to distinguish between Desktop and UWP applications. It would be nice to have this in OpenWatcom since many projects assume that it is always available when building for Windows Desktop.

https://learn.microsoft.com/en-us/cpp/porting/how-to-use-existing-cpp-code-in-a-universal-windows-platform-app?view=msvc-170