> You haven't looked recently, have you?  /usr/src/Makefile says

No - because haven't been able to sup Makefile for ages.  SUP kept
reporting fileserver it can't download src/Makefile and quite a few
others - everything else sup'd ok, permissions etc at both end seem
correct.  This is from my local mirror btw.  Nothing seemed to fix it,
so I just gave up and went back to tar_files - which don't contain
src/Makefile.

The src/Makefile I have has a similar rule in it - but commented out. 

>> Personally I prefer my approach as it is more generally useful.
> 
> Matter of opinion.  I usually prefer that make install just install
> things, without trying to be smart about creating directories where it
> thinks things should go.  In particular, I would _really_ hate it if it
> gets an incorrect idea of where I want to install things and goes wild
> making directories all over my filesystem as a result.

True.  A correct solution would allow both of us a choice.

--sjg