SDL_image: cmake: always build vendored zlib as static library (f261c)

From f261c700115a13859d894b742c87bfee6a7865a1 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 2 Jan 2026 02:03:07 +0100
Subject: [PATCH] cmake: always build vendored zlib as static library

(manual backport of commits b19e40f0 and 4d22f6c2)
---
 CMakeLists.txt | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6b7fda380..25b00f42d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -175,11 +175,7 @@ if(SDL2IMAGE_VENDORED AND SDL2IMAGE_PNG_VENDORED)
 else()
     set(SDL2IMAGE_ZLIB_VENDORED OFF)
 endif()
-if(SDL2IMAGE_PNG_SHARED)
-    set(SDL2IMAGE_ZLIB_SHARED ON)
-else()
-    set(SDL2IMAGE_ZLIB_SHARED OFF)
-endif()
+set(SDL2IMAGE_ZLIB_SHARED OFF)
 
 # Save BUILD_SHARED_LIBS variable
 set(SDL2IMAGE_BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS})
@@ -380,6 +376,9 @@ if(SDL2IMAGE_ZLIB)
         if(NOT TARGET ZLIB::ZLIB)
             add_library(ZLIB::ZLIB ALIAS ${ZLIB_LIBRARY})
         endif()
+        if(NOT TARGET ZLIB::zlibstatic)
+            add_library(ZLIB::zlibstatic ALIAS ${ZLIB_LIBRARY})
+        endif()
         # ZLIB_INCLUDE_DIRS variable is used by vendored libpng
         set(ZLIB_INCLUDE_DIRS "${ZLIB_INCLUDE_DIR}")
         # ZLIB_LIBRARIES variable is used by vendored libpng