Documenting tools necessary for GCC [draft]

[Robert Dewar]

> We only said that we would support Posix-compliant makes.  I'm not sure
> about Irix.  I know that some of the issues on some platforms were because
> of broken vendor makes.

I will not declare anything broken, because you never know what the 
spec is :-)

But for sure let's just say that SGI has critically different semantics in
certain areas compared to other versions of make :-)