Setting NBPAX_PROGRAM_PREFIX by default

["Jonathan Perkin" <jperkin%joyent.com@localhost>]

Hi,

I'd like to set "NBPAX_PROGRAM_PREFIX?= nb" by default.  With
archivers/pax installed I've seen a number of problems building
packages outside of pkgsrc as they assume that on e.g. OSX the version
of 'tar' in path supports --version et al.

My impression is that archivers/pax is mostly a build dependancy these
days, are there any systems that would be broken by this change?  I'd
like to avoid doing this per-platform if possible.

Thanks,

-- 
Jonathan Perkin  -  Joyent, Inc.  -  www.joyent.com