[RFA] Makefile tweaks

[Keith Seitz]

Tom Tromey wrote:
> Please check this in ASAP.

Will do.

> Kyle, please make sure to test changes in the tree before a commit.
> This is the second build-breaker in 2 days ... bad!go
> 
> Keith> At the same time, I'd like to add a dependency for interpret.cc on
> Keith> interpret-run.cc, for obvious reasons.
> 
> Hmm, why did you need this?  It should be taken care of by the
> automatic dependency tracking, and when I look at .deps/interpret.Plo
> I see it mentioned there...

Hmm. Maybe something was borked in an old build? I don't know. I've been 
sitting on this for quite some time. I'll omit it now, and if it occurs 
again, I'll resubmit. [I just checked my build -- it doesn't seem 
necessary.]

I've committed just the regenerated files.

Keith