[PATCH] toplevel bootstrap documentation

[Paolo Bonzini]

> What if it needs to be updated?  If there's any risk that this could
> modify the compiler or any portion of the toolchain it depends on
> while they're already being used, we should point that out or, even
> better, make sure it doesn't happen.
I'm not sure I understand the question, but everything that GCC depends 
on will have been built as part of the bootstrap process, and then will 
be skipped during all-host.

Paolo