mrb_int
To enable multi-precision integer support, you need to link `mruby-bigint` mrbgem. The gem itself is empty but it turns on the "bigint" support.
Internal functions can only be called from within the library. Functions listed in `mruby/internal.h` can be called from: * core (src/*.c) * gems (mrbgems/**/*.c) But not from the application linked with `libmruby`.