SDL: Fixed SDL_RenderSetVSync does not update flags if simulated vsync is on

From d78072fcd46943288a6007cd6f4ab1f98f446b1d Mon Sep 17 00:00:00 2001
From: Ivan Mogilko <[EMAIL REDACTED]>
Date: Sat, 18 Mar 2023 00:39:02 +0300
Subject: [PATCH] Fixed SDL_RenderSetVSync does not update flags if simulated
 vsync is on

This lets the user to correctly detect current vsync state by reading SDL_RendererInfo.
Also fixes SetVSync's return value check (it may be positive for error too).
---
 src/render/SDL_render.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
index 2df36c69a305..422e37a9b390 100644
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -4510,8 +4510,13 @@ int SDL_RenderSetVSync(SDL_Renderer *renderer, int vsync)
     renderer->wanted_vsync = vsync ? SDL_TRUE : SDL_FALSE;
 
     if (!renderer->SetVSync ||
-        renderer->SetVSync(renderer, vsync) < 0) {
+        renderer->SetVSync(renderer, vsync) != 0) {
         renderer->simulate_vsync = vsync ? SDL_TRUE : SDL_FALSE;
+        if (renderer->simulate_vsync) {
+            renderer->info.flags |= SDL_RENDERER_PRESENTVSYNC;
+        } else {
+            renderer->info.flags &= ~SDL_RENDERER_PRESENTVSYNC;
+        }
     } else {
         renderer->simulate_vsync = SDL_FALSE;
     }