(#22097) Use LC_ALL instead of LANG

since LANG doesn't override LC_* when set explicitly:

  $ LC_MESSAGES=de_DE.UTF-8 LANG=C ifconfig
  eth0 Link encap:Ethernet Hardware Adresse 52:54:00:0E:3F:E5
  inet Adresse:10.174.252.56  Bcast:10.174.255.255  Maske:255.255.252.0

See the Adresse vs. the expected addr, whereas:

  $ LC_MESSAGES=de_DE.UTF-8 LC_ALL=C ifconfig
  eth0 Link encap:Ethernet HWaddr 52:54:00:0E:3F:E5
  inet addr:10.174.252.56  Bcast:10.174.255.255  Mask:255.255.252.0

See http://pubs.opengroup.org/onlinepubs/007908799/xbd/envvar.html