PATCH: Fix shared library build for libiberty

[DJ Delorie]

> Just to make sure that everyone understands that we don't build
> libiberty.so for libiberty.

Right, but some distros do.  We don't support them, but they do.

> If we build libiberty.so, we have to be very careful about the ABI.

In general, we are, but not enough for .so's.

> If we don't build libiberty.so, I don't see there is a need for
> libtool. My top level patch is better.

I'd rather use something compatible with all the other libraries, so
that things are more likely to "just work".  Having extra files in
toplevel just for libiberty, when everyeone else is doing something
different, is bad.

Plus, if someone *does* want to make a libiberty.so for themselves,
this would make it a bit easier for them.