cmake JSON_HAS_CPP_17 examples

STEllAR-GROUP/hpx libs/core/command_line_handling_local/cmake/HPX_SetupJSON.cmake :55 

target_compile_definitions(json INTERFACE JSON_HAS_CPP_17)

microsoft/onnxruntime-extensions cmake/externals/json.cmake :7 

add_compile_definitions(JSON_HAS_CPP_17=1)