workaround for microsoft include problems

only for microsoft visual c++ 2010
if users include windows.h and winsock2.h in the wrong
order, things go wrong: windows.h includes winsock.h
with the old API, and winsock2.h will define the new API
even if the old API is already defined, resulting in tons
of redefinition errors.
Defining _WINSOCKAPI_ ensures that winsock.h does not do
anything.
Without this define, pykde would not compile