WIN32 preprocessor macro

[Curt Arnold]

log4cxx  uses the WIN32 preprocessor macro in several places.  
Microsoft Visual C++ and Borland C++ predefine the _WIN32 macro when 
building on Win32, but not WIN32 (Visual Studio will explicitly add a 
/DWIN32 to the command line by default).  I checked the Xerces-C code 
base to see how they handle this and they typically do something like:

#if defined(_WIN32) || defined(WIN32)
which would cause the appropriate Windows specific code to be compiled 
without having to remember to add a /DWIN32 to the command line, but 
would also support a hypothetical compiler that defined WIN32 but not 
_WIN32.  Unless there is a compelling reason to use WIN32 over _WIN32, 
I would suggest changing to either _WIN32 or _WIN32 || WIN32.