windows/SDL_syslocale.c: make it build against older SDKs.

src/locale/windows/SDL_syslocale.c

@@ -24,7 +24,7 @@
 #include "../SDL_syslocale.h"
 #include "SDL_assert.h"
 
-typedef BOOL (WINAPI *pfnGetUserPreferredUILanguages)(DWORD,PULONG,PZZWSTR,PULONG);
+typedef BOOL (WINAPI *pfnGetUserPreferredUILanguages)(DWORD,PULONG,/*PZZWSTR*/WCHAR*,PULONG);
 #ifndef MUI_LANGUAGE_NAME
 #define MUI_LANGUAGE_NAME 0x8 
 #endif