[RFA/commit] use libiconv.a instead of -liconv for in-tree libiconv

[Joel Brobecker]

> That sounds very strange, because I would expect libiconv to always have
> this built in.  Or do you mean that the native iconv doesn't handle
> this?

Oops, yes, sorry, native iconv, not libiconv...

> It seems reasonable to me.

Thanks! If all goes well at AdaCore, I'll commit on our end.
I'll see about adding a comment about our copy being different
from the one we copied from.

-- 
Joel