cpplib: Separate out translation phases 1 and 2

[Neil Booth]

Devang Patel wrote:-

> This will give us bootstrap timing for two different set of sources.
> It is not strictly comparing Apple and Apple.
> 
> I'd do
> - Build gcc1 which does not have your patch
> - Build gcc2 which is gcc1 + your patch
> - Select appropriate GCC sources
> - Build it with gcc1
> - Build same sources with gcc2

Please do.

Neil.