enforce LANG=C for fakeroot

util-linux allows translations of version strings produced by
--version. As a result, fakeroot misbehaves in some locales, but not
others. Enforce LANG=C so that we can get consistent behavior and not
have to worry about crap differences like like:

  $ LANG=C getopt --version
  getopt from util-linux 2.25.388-819d9

  $ LANG=tr_TR.utf8 getopt --version
  util-linux 2.25.388-819d9 deki getopt

  $ LANG=nl_NL.utf8 getopt --version
  'getopt' uit util-linux 2.25.388-819d9

Closes GHI#21.