sdl12-compat: minor warning (C4706) fix

SDL Commits
1 
From bfc8f941eb70a57b24885f841bb05b690a659a12 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Sat, 30 Sep 2023 20:56:04 +0300
Subject: [PATCH] minor warning (C4706) fix

---
 src/SDL12_compat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index de76eb740..864e976cb 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -7696,7 +7696,7 @@ SDL_DisplayYUVOverlay(SDL12_Overlay *overlay12, SDL12_Rect *dstrect12)
 {
     QueuedOverlayItem *overlay;
     SDL12_YUVData *hwdata;
-    SDL_Renderer *renderer = NULL;
+    SDL_Renderer *renderer;
     const SDL_bool ThisIsSetVideoModeThread = (SDL20_ThreadID() == SetVideoModeThread) ? SDL_TRUE : SDL_FALSE;
 
     if (!overlay12) {
@@ -7705,7 +7705,7 @@ SDL_DisplayYUVOverlay(SDL12_Overlay *overlay12, SDL12_Rect *dstrect12)
     if (!dstrect12) {
         return SDL20_InvalidParamError("dstrect");
     }
-    if (!(renderer = LockVideoRenderer())) {
+    if ((renderer = LockVideoRenderer()) == NULL) {
         return SDL20_SetError("No software screen surface available");
     }