SDL: SDL_UnionRect: If both rects are empty, zero out the result struct.

SDL Commits
1 
From c573ebe1439e51e6b50f2ec37c381d13d643fe22 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sat, 19 Mar 2022 09:29:01 -0400
Subject: [PATCH] SDL_UnionRect: If both rects are empty, zero out the result
 struct.

---
 src/video/SDL_rect.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/video/SDL_rect.c b/src/video/SDL_rect.c
index 0c929517cf2..dd2c7bc7ab4 100644
--- a/src/video/SDL_rect.c
+++ b/src/video/SDL_rect.c
@@ -148,6 +148,7 @@ SDL_UnionRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
     if (SDL_RectEmpty(A)) {
       if (SDL_RectEmpty(B)) {
        /* A and B empty */
+       SDL_zerop(result);
        return;
       } else {
        /* A empty, B not empty */