remove libspng mentions from Windows build

src/CMakeLists.txt

@@ -24,7 +24,6 @@ if (WIN32)
       set(LUA_LIBRARIES "${CMAKE_CURRENT_SOURCE_DIR}/../vcpkg/packages/luajit_x64-windows/lib/lua51.lib")
       set(LUA_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../vcpkg/packages/luajit_x64-windows/include/luajit")
       find_package(glfw3 REQUIRED)
-      find_package(spng REQUIRED)
       find_package(glm REQUIRED)
       find_package(vorbis REQUIRED)
       set(VORBISLIB Vorbis::vorbis Vorbis::vorbisfile)

src/coders/png.cpp

@@ -11,9 +11,7 @@
 
 static debug::Logger logger("png-coder");
 
-#ifndef _WIN32
 #define LIBPNG
-#endif
 
 #ifdef LIBPNG
 #include <png.h>

vcpkg.json

@@ -7,7 +7,7 @@
       "glfw3",
       "glew",
       "glm",
-      "libspng",
+      "libpng",
       "zlib",
       "luajit",
       "libvorbis",