SDL: Fix -Wmissing-prototypes warning

SDL Commits
1 
From ac72cdcf79508a2ff9032429cc1dca0822b0b0f7 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Wed, 5 Apr 2023 05:38:27 +0200
Subject: [PATCH] Fix -Wmissing-prototypes warning

./src/video/SDL_video.c:1734:13: warning: no previous prototype for function 'SDL_CreateWindowInternal' [-Wmissing-prototypes]
SDL_Window *SDL_CreateWindowInternal(const char *title, int x, int y, int w, int h, SDL_Window *parent, Uint32 flags)
            ^
./src/video/SDL_video.c:1734:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
SDL_Window *SDL_CreateWindowInternal(const char *title, int x, int y, int w, int h, SDL_Window *parent, Uint32 flags)
^
static
---
 src/video/SDL_video.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
index aaf99ab18a0b..ffd4f96a0e65 100644
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -1731,7 +1731,7 @@ static int SDL_DllNotSupported(const char *name)
     return SDL_SetError("No dynamic %s support in current SDL video driver (%s)", name, _this->name);
 }
 
-SDL_Window *SDL_CreateWindowInternal(const char *title, int x, int y, int w, int h, SDL_Window *parent, Uint32 flags)
+static SDL_Window *SDL_CreateWindowInternal(const char *title, int x, int y, int w, int h, SDL_Window *parent, Uint32 flags)
 {
     SDL_Window *window;
     Uint32 type_flags, graphics_flags;