sdl12-compat: Don't set SDL_DOUBLEBUF on the screen surface

SDL Commits
1 
From 9fbe20dab136ed0c9abbe73872dd5e38d6b6102f Mon Sep 17 00:00:00 2001
From: David Gow <[EMAIL REDACTED]>
Date: Mon, 31 May 2021 19:18:18 +0800
Subject: [PATCH] Don't set SDL_DOUBLEBUF on the screen surface

This causes problems with programs which don't handle the combination of
SDL_DOUBLEBUF on a surface which doesn't need locking (i.e.
SDL_HWSURFACE not being set) properly.

DOSBox is one such application, so this fixes issue #58.

It also matches what the real SDL 1.2 exposes in most real-world
circumstances.
---
 src/SDL12_compat.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 77566b1..e67a53a 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -3584,7 +3584,6 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)
         }
 
         VideoSurface12->flags &= ~SDL12_OPENGL;
-        VideoSurface12->flags |= SDL12_DOUBLEBUF;
         VideoSurface12->surface20->pixels = SDL20_malloc(height * VideoSurface12->pitch);
         VideoSurface12->pixels = VideoSurface12->surface20->pixels;
         if (!VideoSurface12->pixels) {