message: Update library file names `libpng12` -> `libpng16`
diff: @@ -23,24 +23,24 @@ set(png_INSTALL ${CMAKE_BINARY_DIR}/png/install)
  if(WIN32)
  if(${CMAKE_GENERATOR} MATCHES "Visual Studio.*")
  set(png_STATIC_LIBRARIES
  - debug ${CMAKE_BINARY_DIR}/png/install/lib/libpng12_staticd.lib
  - optimized ${CMAKE_BINARY_DIR}/png/install/lib/libpng12_static.lib)
  + debug ${CMAKE_BINARY_DIR}/png/install/lib/libpng16_staticd.lib
  + optimized ${CMAKE_BINARY_DIR}/png/install/lib/libpng16_static.lib)
  else()
  if(CMAKE_BUILD_TYPE EQUAL Debug)
  set(png_STATIC_LIBRARIES
  - ${CMAKE_BINARY_DIR}/png/install/lib/libpng12_staticd.lib)
  + ${CMAKE_BINARY_DIR}/png/install/lib/libpng16_staticd.lib)
  else()
  set(png_STATIC_LIBRARIES
  - ${CMAKE_BINARY_DIR}/png/install/lib/libpng12_static.lib)
  + ${CMAKE_BINARY_DIR}/png/install/lib/libpng16_static.lib)
  endif()
  endif()
  else()
  - set(png_STATIC_LIBRARIES ${CMAKE_BINARY_DIR}/png/install/lib/libpng12.a)
  + set(png_STATIC_LIBRARIES ${CMAKE_BINARY_DIR}/png/install/lib/libpng16.a)
  endif()
  set(png_HEADERS
  - "${png_INSTALL}/include/libpng12/png.h"
  - "${png_INSTALL}/include/libpng12/pngconf.h"
  + "${png_INSTALL}/include/libpng16/png.h"
  + "${png_INSTALL}/include/libpng16/pngconf.h"
  )
  ExternalProject_Add(png
  