sdl2-compat: video: SDL_GL_SwapWindow doesn't return void in SDL3.

From e4823feb40d93aa339155dd60f1d309037bf25cc Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 29 Dec 2022 14:15:22 -0500
Subject: [PATCH] video: SDL_GL_SwapWindow doesn't return void in SDL3.

---
 src/sdl2_compat.c | 7 +++++++
 src/sdl3_syms.h   | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/sdl2_compat.c b/src/sdl2_compat.c
index 96bc035..5fc1006 100644
--- a/src/sdl2_compat.c
+++ b/src/sdl2_compat.c
@@ -2901,6 +2901,13 @@ SDL_GetWindowFlags(SDL_Window *window)
     return flags;
 }
 
+/* SDL3 added a return value. We just throw it away for SDL2. */
+DECLSPEC void SDLCALL
+SDL_GL_SwapWindow(SDL_Window *window)
+{
+    (void) SDL3_GL_SwapWindow(window);
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/sdl3_syms.h b/src/sdl3_syms.h
index 4b0b887..4059fed 100644
--- a/src/sdl3_syms.h
+++ b/src/sdl3_syms.h
@@ -569,7 +569,7 @@ SDL3_SYM_PASSTHROUGH(SDL_GLContext,GL_GetCurrentContext,(void),(),return)
 SDL3_SYM_PASSTHROUGH(void,GL_GetDrawableSize,(SDL_Window *a, int *b, int *c),(a,b,c),)
 SDL3_SYM_PASSTHROUGH(int,GL_SetSwapInterval,(int a),(a),return)
 SDL3_SYM_PASSTHROUGH(int,GL_GetSwapInterval,(void),(),return)
-SDL3_SYM_PASSTHROUGH(void,GL_SwapWindow,(SDL_Window *a),(a),)
+SDL3_SYM(int,GL_SwapWindow,(SDL_Window *a),(a),return)
 SDL3_SYM_PASSTHROUGH(void,GL_DeleteContext,(SDL_GLContext a),(a),)
 SDL3_SYM_PASSTHROUGH(int,vsscanf,(const char *a, const char *b, va_list c),(a,b,c),return)
 SDL3_SYM(int,AddGamepadMappingsFromRW,(SDL_RWops *a, int b),(a,b),return)