locale aliases, and new gettext.m4

[coypu%sdf.org@localhost]

Hi folks.

An up to date gettext.m4 is failing for lacking _nl_expand_alias.
This means NLS is being disabled on netbsd for many packages, and not on
illumos or linux, which is very annoying to handle in pkgsrc.

I have no strong opinions on locale aliases, but we may want to do
something about this, here are some options:

1. complain at whoever wrote gettext.m4, if we think locale aliases are
silly.
2. implement dummy _nl_expand_alias, e.g. return NULL. this is done by
uClibc.
3. implement a real _nl_expand_alias

Thoughts, discussion, etc.