Install libpng in the macOS job

Thanks to Andreas Grabher for some hints on how to build the png.framework.

.cirrus.yml

@@ -15,9 +15,10 @@ freebsd_task:
 
 macos12_task:
   osx_instance:
-    image: ghcr.io/cirruslabs/macos-monterey-xcode:13
+    image: ghcr.io/cirruslabs/macos-monterey-xcode:latest
   env:
     SDLVERSION: 2.26.5
+    PNGVERSION: 1.6.40
   download_cache:
     folder: dl_cache
     populate_script:
@@ -26,9 +27,21 @@ macos12_task:
           wget -O dl_cache/SDL2-$SDLVERSION.dmg
             https://github.com/libsdl-org/SDL/releases/download/release-$SDLVERSION/SDL2-$SDLVERSION.dmg ;
         fi
+      - if [ ! -e dl_cache/png.framework ]; then
+          wget -O dl_cache/libpng-$PNGVERSION.tar.xz
+            "http://prdownloads.sourceforge.net/libpng/libpng-$PNGVERSION.tar.xz?download" ;
+          tar -xJf dl_cache/libpng-$PNGVERSION.tar.xz ;
+          cd libpng-$PNGVERSION ;
+          cmake -DCMAKE_OSX_DEPLOYMENT_TARGET:STRING="10.9" -DPNG_FRAMEWORK=ON
+                -DPNG_HARDWARE_OPTIMIZATIONS=OFF . ;
+          cmake --build . --verbose --config Release -j$(sysctl -n hw.ncpu) ;
+          cd .. ;
+          mv libpng-$PNGVERSION/png.framework dl_cache/ ;
+        fi
   install_script:
     - hdiutil attach dl_cache/SDL2-$SDLVERSION.dmg
     - sudo cp -a /Volumes/SDL2/SDL2.framework /Library/Frameworks/
+    - sudo cp -a dl_cache/png.framework /Library/Frameworks/
   script:
     - export PATH=/usr/local/bin:$PATH
     - mkdir build
@@ -37,6 +50,7 @@ macos12_task:
       || { cat config.log; exit 1; }
     - cmake --build . --verbose --config Release -j$(sysctl -n hw.ncpu) -t hatari
     - cp -a /Volumes/SDL2/SDL2.framework src/hatari.app/Contents/Frameworks/
+    - cp -a ../dl_cache/png.framework src/hatari.app/Contents/Frameworks/
     - codesign --force --deep --options=runtime -s -
       --entitlements ../src/gui-osx/hatari.app.xcent src/hatari.app
     - cd ..