Improve OBJDIR detection.

Uses buildenv to grab the real obj prefix and concatenates
the source directory. Only testes on 9+ so I left the 9 case
in place.
Merge pull request #33 from dannomac/fix_objdir

Improve OBJDIR detection.
Merge branch 'master' of git://github.com/kientzle/crochet-freebsd into make-jobs