lisp-invocation: play nicer with recent SBCL.
disable rucksack for now until issues with latest SBCL are resolved.

driver: Be more robust when borking or otherwise dying.
TODO: ABCL fork hints.

* More but still incomplete support for mkcl and cormanlisp.

Also export some command-line related symbols from the driver.

into the encodings feature. utf-8 is the default encoding and use :default
at your own risk. Anything else gets delegated to asdf-encodings.

Make sure we (re)initialize-asdf at some early point: things may have changed after image-dump.

Fix tests with SBCL, too.
Remove obsolete setup.lisp for good. We are in an asdf 2 world!