separate assembly

[Stephen Weeks]

> > Ideally, I'd like to make everything global, do the assembly
> > and the incremental link, then patch that object file so that only
> > gcReturns and entries are global, and everything else is local.
> 
> Hmmm, could the patch happen after linking with the C stub?  Then nothing is
> global other than the library routines.

Now that I think about it, I'm a bit worried about patching object files.  It
sounds like another barrier to portability that we should avoid if possible.
I think I'd rather just pick some "safe" label naming convention, and possibly
have a command line argument that lets you pick the label prefix.