Have a single internal classes dir even in a non-deployjar bundle.

This restores the status quo ante.

This turns out to make the code a lot simpler too.

The terminology 'deployjar' is confusing, so I changed the name
of the internal method deployjar() to loose_classfiles_jar(), which
is more descriptive. However I left the term 'deployjar' in the
cmd-line flag name, for backwards compatibility.