sdl12-compat: Don't mark the screen surface as SDL_HWSURFACE.

From b9d3a68f37850f9087c1e6e457137c4d5117d016 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Mon, 31 May 2021 00:09:53 -0400
Subject: [PATCH] Don't mark the screen surface as SDL_HWSURFACE.

I'm not sure what this was meant to fix, based on the related comment, but
it causes a problem with the port of Build Engine's editor,
which will lock the screen surface because SDL_MUSTLOCK sees SDL_HWSURFACE
and (a bug!) won't unlock it again, causing disaster.

In sdl12-compat, the screen surface is _never_ actually a HWSURFACE; it's
always a buffer of pixels in RAM, not lockable VRAM memory; how we get it to
the screen after that is just an implementation detail, the same as it was
in 1.2 when it might have gone through an X11 server or through win32 GDI.

But we might have to adjust plans here if that SDL_HWSURFACE flag turns out
to have had a specific app in mind to fix, though.

Fixes #71.
 src/SDL12_compat.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 157c592..77566b1 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -3585,9 +3585,6 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)
         VideoSurface12->flags &= ~SDL12_OPENGL;
         VideoSurface12->flags |= SDL12_DOUBLEBUF;
-        /* some apps check for the presence/lack of double buffering via MUSTLOCK
-         * so set SDL12_HWSURFACE so they are less confused */
-        VideoSurface12->flags |= SDL12_HWSURFACE;
         VideoSurface12->surface20->pixels = SDL20_malloc(height * VideoSurface12->pitch);
         VideoSurface12->pixels = VideoSurface12->surface20->pixels;
         if (!VideoSurface12->pixels) {