%L NLSPATH handling: just use locale name, skip language code

[jelmd]

Right now ast's NLSPATH resolver creates 2 paths to search for a catalog if it encounters a %L: one time it gets replaced by the locale name (as POSIX suggests) and in the 2nd variant it gets replaced by the locale's language code (unless both are equal), e.g. with 'de_DE' and 'de'. Couldn't find any specs, which says to do it this way (i.e. to generate a 2nd variant, where %L gets replaced by language code). It also seems to be redundant, because if one really wants to include a ${language_code}/ dir in the catalog lookup, one can do it by adding a the same path to NLSPATH but having %L replaced by %l.

So finally the resolver should replace %L just by the locale name, and that's it (would simplify the related code as well).