`rp` and other commands were broken for me because they always showed
the object as a T_NONE.

The reason was that instead of returning the type `struct RBasic`,
FindFirstType("struct RBasic") was returning
`yjit::cruby::autogened::RBasic`.

Explicitly asking for the top-level RBasic by prefixing it with `::` is
enough to fix those commands.