System definition mode-line has wrong package

[Symbolics]

The system definition mode line specifies a package of CL-USER, however the correct package name is ASDF. On many platforms, asdf takes care of this, but on Genera the mode line is honored and therefore defsystem is not a known symbol. Either the mode line can be patched, or the fully qualified symbol used, e.g. asdf:defsystem.

[Symbolics]

Some additional investigation shows that a file attribute is required in packages.lisp as well. I've closed the pull request until I can go through all the changes and do a bit more testing.