make make.conf(5) works again

with my patch to tinderbox, make.conf hack works again. i am not sure at
the moment whether if we discard "env" completely and in which file you
should define environment variables.

https://gist.github.com/trombik/4760968

see also
http://marcuscom.com/pipermail/tinderbox-list/2013-January/002873.html
Merge branch 'master' of github.com:reallyenglish/reallyenglish-tinderbox-scripts