cJSON里的一段宏定义不知道该怎么理解
#if defined(CJSON_HIDE_SYMBOLS)
#define CJSON_PUBLIC(type) type CJSON_STDCALL
#elif defined(CJSON_EXPORT_SYMBOLS)
#define CJSON_PUBLIC(type) __declspec(dllexport) type CJSON_STDCALL
#elif defined(CJSON_IMPORT_SYMBOLS)
#define CJSON_PUBLIC(type) __declspec(dllimport) type CJSON_STDCALL
#endif
#else /* !__WINDOWS__ */
#define CJSON_CDECL
#define CJSON_STDCALL