cmake FO_HAVE_METAL examples

cvet/fonline BuildTools/StartGeneration.cmake :521

add_compile_definitions(FO_HAVE_OPENGL=${FO_HAVE_OPENGL} FO_OPENGL_ES=${FO_OPENGL_ES} FO_HAVE_DIRECT_3D=${FO_HAVE_DIRECT_3D} FO_HAVE_METAL=${FO_HAVE_METAL} FO_HAVE_VULKAN=${FO_HAVE_VULKAN})