patch: PR libc/2254: make locale(1) report errors and improve help

[Petter Reinholdtsen]

[Ulrich Drepper]
> I've applied the patch, but not this chunk.  It not better than
> nothing at all.

If you say so.

> If you want to see documentation write an appropriate toplevel info
> file.  It shouldn't be in the libc hierachy.

I'll leave the documentation writing to someone else.  I updated PR
2254 to document that it is only the documentation part that is
missing.  Why shouldn't the arguments to locale tool be documented in
the libc hierarchy.