[quotes reordered for replying convenience]

> E.g. NOCLEANDIR is essentially the same as "build.sh -u", no?

Close, but nto quite; -u sets MKUPDATE, which does more than just
NOCLEANDIR.

> USETOOLS is, it seems to me, mandatory -- as far as I can see you
> can't override it -- it is always set to "yes" when using build.sh

That seems like a bug to me; you should be able to do something like
"USETOOLS=never build.sh -D / build" to get more or less the effect of
a pre-build.sh "make build".

> TOOLDIR is definitely settable with "build.sh -T"

> I think all the rest can be controlled with "build.sh -V var=value"

Hm, despite my multiple readings through BUILDING, I managed to miss
those.  Thanks for pointing them out - and in the process pointing up a
problem with build.sh: it presents a form of feature overload, enough
that I missed two important things during multiple read-throughs of
BUILDING.

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