Aha, it seems that this part from BUILDING is not true:

     USETOOLS    Indicates whether the tools specified by TOOLDIR should be
                 used as part of a build in progress.  Must be set to ``yes''
                 if cross-compiling.

                 yes    Use the tools from TOOLDIR.
...
                 Default: ``yes'' if building all or part of a whole NetBSD
                 source tree (detected automatically); ``no'' otherwise (to
                 preserve traditional semantics of the <bsd.*.mk> make(1) in-
                 clude files).

In fact, USETOOLS is set neither in build.sh nor in the toplevel
Makefile. It looks like it ought to get set in bsd.own.mk, but
apparently it doesn't.

Manually setting it to yes (in the environment) makes things a lot better.

-Olaf.
-- 
___ Olaf 'Rhialto' Seibert - rhialto@     --Soep van de dag, wat zal dat zijn
\X/ xs4all.nl --wat kan dat wezen, beter maar het ergste vrezen -Boy Bensdorp