SDL: wayland: Check the returned display value for null

SDL Commits
1 
From 91bb1bb6fd042677c2725a1c9e6e99cb71dda247 Mon Sep 17 00:00:00 2001
From: Frank Praznik <[EMAIL REDACTED]>
Date: Tue, 3 Dec 2024 11:53:14 -0500
Subject: [PATCH] wayland: Check the returned display value for null

In reality, this condition will never occur, since the index is checked before calling the display retrieval function, but aggressive LTO with jump threading can generate a warning if this isn't explicitly checked.
---
 src/video/wayland/SDL_waylandvideo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/video/wayland/SDL_waylandvideo.c b/src/video/wayland/SDL_waylandvideo.c
index 0aa26956252d6..b053cfa2a4b20 100644
--- a/src/video/wayland/SDL_waylandvideo.c
+++ b/src/video/wayland/SDL_waylandvideo.c
@@ -647,6 +647,11 @@ static void display_handle_done(void *data,
 
     if (driverdata->index > -1) {
         dpy = SDL_GetDisplay(driverdata->index);
+
+        /* XXX: This can never happen, but jump threading during aggressive LTO can generate a warning without this check. */
+        if (!dpy) {
+            dpy = &driverdata->placeholder;
+        }
     } else {
         dpy = &driverdata->placeholder;
     }