Self-compile/cross compile:

Figure out how the compiler can compile itself in a virgin environment.
RENAME-PACKAGE is probably nearly enough.
 -- if we change the debug-info format, things are a bit ucky, since these
    structures are used both at compile time and run time.  Probably we should
    move the debug-info out of compiler so that it doesn't get renamed, then
    compile and load debug-info.  This shouldn't break the running Lisp in any
    important way, since we only make debug-info's at compile time, and at
    run-time all of the accessors are open-coded assuming the format present at
    compile time.  [The only problem I can think of is that the default print
    function, #S reader, inspector, etc., would not be able to properly
    understand debug-info anymore.  But none of these operations are important
    for debug-info; the debugger would still work.]  But for this to work, we
    would also have to compile and load debug-dump, which might not be possible
    without some hacking.  Alternately, we could just ignore the debug-info
    issue, which would result in a core that produces the new debug-info
    format, but has all its debug-info in the old format.  We could then
    iterate to fix stuff up, but it would be hard to debug.  I guess our
    default virgin compile should ignore debug info issues, and then we do some
    specific bootstrap action when we change.  We may want to leave debug-info
    in compiler, since we can always load the bootstrap code into old-compiler.