which includes Makefile.nbincludes, whose beforedepend: has
some race condition I don't fully understand, and which has been
causing many (but not all!) -j16 builds on the autobuild cluster
to fail in tools since sometime between 201103061600 and 201103070900.
With the proper voodoo, I was able to get 8 builds in a row to fail
without this change, and 16 in a row to succeed with it.
XXX a proper fix likely involves reworking the beforedepend: target
of Makefile.nbincludes, but this should get the build cluster back up
to full functionality in the meanwhile.
c8735093ef