devel/redasm: pending the update, unbreak the port's build

Relax REDasm::Emulator::remap() method access from private
to protected, as it is being called from the derived class,
and fix a minor GUI bug while I'm here.

There are newer versions available, but those have various
run-time (3.0.0-beta5 segfaults on start) or build (4.0.0-
beta1 is a massive rewrite) issues to be taken care of.

Reported by: pkg-fallout