SDL_image: upgrade vendored libpng to v1.6.58 (11643)

From 1164340e16b95ac735c093aa67280dad737eaf2f Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 17 Apr 2026 14:10:50 +0300
Subject: [PATCH] upgrade vendored libpng to v1.6.58

(cherry picked from commit e4b3811eb83dbd40f88d61faf92e7d0458d8d8a4)
---
 .gitmodules     | 2 +-
 external/libpng | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.gitmodules b/.gitmodules
index ac19bac0..c13a57d2 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -5,7 +5,7 @@
 [submodule "external/libpng"]
 	path = external/libpng
 	url = https://github.com/libsdl-org/libpng.git
-	branch = v1.6.56-SDL
+	branch = v1.6.58-SDL
 [submodule "external/libwebp"]
 	path = external/libwebp
 	url = https://github.com/libsdl-org/libwebp.git
diff --git a/external/libpng b/external/libpng
index 48aeba5a..4b9e071b 160000
--- a/external/libpng
+++ b/external/libpng
@@ -1 +1 @@
-Subproject commit 48aeba5a640b710b8533b0231aec1b3bb501f0cb
+Subproject commit 4b9e071b2fc4216369372a3ed260d335dd036f15