I tried to add WIN32_LEAN_AND_MEAN as a preprocessor macro for Windows extension, but seems it is not allowed.
By default, Windows.h includes WinSock.h, which cannot co-exists with WinSock2.h, please see this link for more detail.
Macro WIN32_LEAN_AND_MEAN will make Windows.h exclude WinSock.h, (please see this link for more detail).
I need this macro badly becuase I need to include WinSock2.h in my extension.