re: Toolifying nbmake properly?

[matthew green <mrg%eterna.com.au@localhost>]

> What about the attached patch?
> 
> Providing a default for NETBSDSRCDIR in buildmake.sh.in is just a
> precaution, as build.sh should always set it.
> 
> My change to sets.subr to use explicit -m should probably stay b/c I
> think in theory we still support no-tools in-place builds, in which
> case we do want host's make to use mk files from the tree.  This is
> normally taken care of with MAKEFLAGS, but we unset it there.
> 
> kre@ - do you remember the reason for that change to drop it?

if this patch works, LGTM.  thanks!