How to make locale settings more robust

[Anadon]

Hello all,

As always, I may be posting in an almost correct mailing list.

I am trying to get the locale strings "uk", "uk_UA", and "uk_UA.utf8"
to all work similarly.  Currently, only the latter works.

```
LC_ALL=uk_UA.utf8 LANGUAGE=uk_UA.utf8
LOCALEDIR=/home/anadon/Documents/code/primes/po LANG=uk_UA.utf8
LC_MESSAGES=uk_UA.utf8 LC_TYPE=uk_UA.utf8 LANG=uk_UA.utf8  strace
./build/src/primes --help
```

locale -a yields
```
C
C.utf8
en_AG
en_AG.utf8
en_AU.utf8
en_BW.utf8
en_CA.utf8
en_DK.utf8
en_GB.utf8
en_HK.utf8
en_IE.utf8
en_IL
en_IL.utf8
en_IN
en_IN.utf8
en_NG
en_NG.utf8
en_NZ.utf8
en_PH.utf8
en_SG.utf8
en_US.utf8
en_ZA.utf8
en_ZM
en_ZM.utf8
en_ZW.utf8
POSIX
uk_UA.utf8
```

which looks related.  I just don't know how it is related, nor where I
would search for this documentation.