SF bug 418296: WinMain.c should use WIN32_LEAN_AND_MEAN.

I believe Kevin Rodgers here!  The old WINDOWS_LEAN_AND_MEAN has, AFAICT,
always been wrong.

Misc/ACKS

@@ -323,6 +323,7 @@ Nicholas Riley
 Jean-Claude Rimbault
 Andy Robinson
 Jim Robinson
+Kevin Rodgers
 Mike Romberg
 Case Roole
 Timothy Roscoe

PC/WinMain.c

 /* Minimal main program -- everything is loaded from the library. */
 
-#define WINDOWS_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
 #include "Python.h"