devel/exomizer: Add new port

[zirias]

Summary

Exomizer is a cruncher for old 8-bit computers, with focus on the MOS
6502 CPU. It can create self-decrunching executables for a variety of
these systems, as well as plain crunched data. Some decrunching code
for the target systems is bundled.

[zirias]

Avoid patching the upstream Makefile.

Also fix a typo in the commit message.

[tcberner]