More consistent usage of locale variables

[Removed by request]

I'm using Ubuntu 16.04 dev with libc-bin 2.21-0ubuntu6 and for example on this output I'm noticing different variants of the values used:

sworddragon@ubuntu:~$ echo $LANG
de_DE.UTF-8
sworddragon@ubuntu:~$ locale -a
C
C.UTF-8
de_AT.utf8
de_BE.utf8
de_CH.utf8
de_DE.utf8
de_LI.utf8
de_LU.utf8
en_US.utf8
POSIX

$LANG uses "UTF-8" at the end instead of "utf8" as in the locale list. Also C.UTF-8 uses a different end as the other unicode-base locales in the list. Maybe this could be made more consistent so that overall one variant is preferred.