updated json spec to the new __DIR__ handling
updated json spec to the new __DIR__ handling

protobuf-php/protobuf,datto/Protobuf-PHP,sylar94444/Protobuf-PHP,datto/Protobuf-PHP,drslump/Protobuf-PHP,geneanet/Protobuf-PHP,felipernb/Protobuf-PHP,miniplay/Protobuf-PHP,rgooding/Protobuf-PHP,drslump/Protobuf-PHP,miniplay/Protobuf-PHP,sylar94444/Protobuf-PHP,yiliaofan/Protobuf-PHP,stanley-cheung/Protobuf-PHP,felipernb/Protobuf-PHP,centraldesktop/Protobuf-PHP,drslump/Protobuf-PHP,rgooding/Protobuf-PHP,rgooding/Protobuf-PHP,datto/Protobuf-PHP,protobuf-php/protobuf,stanley-cheung/Protobuf-PHP,yiliaofan/Protobuf-PHP