A bootstrap-ultralean patch

[Joe Buck]

> I made this patch to allow
> 
> # make bootstrap-ultralean
> 
> which only builds the C compiler for stage 1. It saves both CPU
> time and disk space.

The problem with this is that the resulting binary will differ from
the binary produced by a normal bootstrap.  It would be particularly
troublesome if you (or anyone else) were ever to distribute a
binary release of a gcc produced by this method, resulting possibly
in bug reports that cannot be duplicated.

At least do stage 2 (the only purpose for stage 3 is the check).