Excude whole libs when building w32 dlls with -export-all

[Ralf Habacker]

> I too like the patch Danny has put forward, (not that I didn't speak
> against it :]). I'm hoping to review Ralf's patch tomorrow & will try
> and get to Danny's as well. I'm going to test on a non-HEAD ld, and if
> that works correctly, then IMO it can go into HEAD... as long as that
> part hasn't altered significantly between my testpoint and HEAD.

I have applied this already to the CVS head. I works. :-)
Ralf