More Cygwin compiler warnings...

--HG--
branch : SDL-1.2

src/video/wincommon/SDL_sysevents.c

@@ -762,7 +762,10 @@ int SDL_RegisterApp(char *name, Uint32 style, void *hInst)
 #ifndef NO_GETKEYBOARDSTATE
 	/* Initialise variables for SDL_ToUnicode() */
 	codepage = GetCodePage();
-	SDL_ToUnicode = Is9xME() ? ToUnicode9xME : ToUnicode;
+
+	/* Cygwin headers don't match windows.h, so we have to cast around a
+	   const issue here... */
+	SDL_ToUnicode = Is9xME() ? ToUnicode9xME : (ToUnicodeFn) ToUnicode;
 #endif
 
 	app_registered = 1;