Need JSON-related compile option support.

[grysgreat]

Background

Currently, the rapidjson library is not installed in some use environments, and compilation options need to be added to the library to support different environment requirements.

Describe the solution you'd like

Add compilation options to your RapidJson-related code

[hongriTianqi]

This is a good practice as it gives an example on how to add a compile option to include an external library.