dep/msvc: Update SDL2 to 2.0.16

dep/msvc/sdl2/include/SDL_egl.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -390,6 +390,9 @@ typedef enum {
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN 1
 #endif
+#ifndef NOMINMAX   /* don't define min() and max(). */
+#define NOMINMAX
+#endif
 #include <windows.h>
 
 #if __WINRT__