SDL: Use dispatch_async for -[NSOpenGLContext update]. Fixes #3680

SDL Commits
1 
From 033c0abb58e7aa6ba2bf7ad4952b73d9061f3f59 Mon Sep 17 00:00:00 2001
From: Learath <[EMAIL REDACTED]>
Date: Sat, 27 Mar 2021 14:04:00 +0100
Subject: [PATCH] Use dispatch_async for -[NSOpenGLContext update]. Fixes #3680

---
 src/video/cocoa/SDL_cocoaopengl.m | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/video/cocoa/SDL_cocoaopengl.m b/src/video/cocoa/SDL_cocoaopengl.m
index 76d35219c..fc200ff5d 100644
--- a/src/video/cocoa/SDL_cocoaopengl.m
+++ b/src/video/cocoa/SDL_cocoaopengl.m
@@ -135,7 +135,7 @@ - (void)explicitUpdate
     if ([NSThread isMainThread]) {
         [super update];
     } else {
-        dispatch_sync(dispatch_get_main_queue(), ^{ [super update]; });
+        dispatch_async(dispatch_get_main_queue(), ^{ [super update]; });
     }
 }