[RDY] Remove project-specific integer types: long_u. (2)

This is part of a series of PR's aimed at removing long_u from the codebase.
This PR deals with the following instances of long_u:

- Those within *eval* module.
- Those within *memfile* module.

It continues the work in #656, #757 towards fulfilling #459.
Are we planning to change `got_int` to bool? I noticed that line 494 has:

    got_int |= got_int_save;

While we're here, seems like a good time to change it to:

    got_int = got_int_save || got_int;