SDL_image: IMG_libpng.c: fix build error due to -Wsign-compare (a921c)

SDL Commits
1 
From a921c7f56ebe612904b21c6895bf29630f04c97f Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 1 May 2026 07:56:40 +0300
Subject: [PATCH] IMG_libpng.c: fix build error due to -Wsign-compare

(cherry picked from commit f3c2cd623ce125eee77e316b6ba479368d72c0b1)
---
 src/IMG_libpng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/IMG_libpng.c b/src/IMG_libpng.c
index c8102663..eb3eb125 100644
--- a/src/IMG_libpng.c
+++ b/src/IMG_libpng.c
@@ -1502,7 +1502,7 @@ bool IMG_CreateAPNGAnimationDecoder(IMG_AnimationDecoder *decoder, SDL_Propertie
         }
     }
 
-    if (!ctx->is_apng || ctx->fctl_count == 0 || ctx->actl.num_frames > ctx->fctl_count) {
+    if (!ctx->is_apng || ctx->fctl_count == 0 || ctx->actl.num_frames > (unsigned int)ctx->fctl_count) {
         SDL_SetError("Not an APNG file or not enough frame control chunks found");
         IMG_AnimationDecoderClose_Internal(decoder);
         return false;