[DVDnav-discuss] [PATCH] do not rely on _WIN32 #define

Newer versions of Cygwin no longer set the _WIN32 #define. This is causing some problems that we worked around locally in MPlayer. I have replaced it with WIN32, which is used in other places in libdvdread, but possibly using __MINGW32__ and __CYGWIN__ is even better and makes the intent clearer. I'd appreciate if somebody could test this since I have no Windows system. I think libdvdread is supposed to build on Visual Studio as well, so testing that would be a bonus. Diego