fix

Author: nyfair

3rdparty/libpng/CMakeLists.txt

@@ -1140,3 +1140,4 @@ endif()
 # TODO: Create MSVC import lib for MinGW-compiled shared lib.
 # pexports libpng.dll > libpng.def
 # lib /def:libpng.def /machine:x86
+INCLUDE_DIRECTORIES(${CMAKE_BINARY_DIR}/3rdparty/zlib-ng)