pngminus: Add a CMakeLists file
diff --git a/contrib/pngminus/CMakeLists.txt b/contrib/pngminus/CMakeLists.txt
new file mode 100644
index 0000000..1f815a5
--- /dev/null
+++ b/contrib/pngminus/CMakeLists.txt
@@ -0,0 +1,24 @@
+cmake_minimum_required(VERSION 3.1)
+cmake_policy(VERSION 3.1)
+
+project(PNGMINUS C)
+
+option(PNGMINUS_USE_STATIC_LIBRARIES "Use the static library builds" ON)
+
+# libpng
+add_subdirectory(../.. libpng)
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../..)
+include_directories(${CMAKE_CURRENT_BINARY_DIR}/libpng)
+if(PNGMINUS_USE_STATIC_LIBRARIES)
+ set(PNGMINUS_PNG_LIBRARY png_static)
+else()
+ set(PNGMINUS_PNG_LIBRARY png)
+endif()
+
+# png2pnm
+add_executable(png2pnm png2pnm.c)
+target_link_libraries(png2pnm ${PNGMINUS_PNG_LIBRARY})
+
+# pnm2png
+add_executable(pnm2png pnm2png.c)
+target_link_libraries(pnm2png ${PNGMINUS_PNG_LIBRARY})
