Searching configured and relocated prefix.

[Paul Brook]

> > (1b) If the configure-time prefix does not exist, but is under an NFS
> > mount, the compiler will cause automount traffic, NFS timeouts, etc.
>...
> > However, I think it's clear that the problems in (1) are more severe
> > than the problems in (2), on several grounds:
>
> I actually think the problems with 1 (b) are artificial and should not
> be taken into account.

1(b) is a common and very real problem, especially on windows hosts.
A hardcoded drive letter is pretty much guaranteed to be wrong. It makes the 
compiler unusable if that drive happens to be a removable drive or network 
share on the user's machine.

Paul