java.endorsed.dirs plan

[Tom Tromey]

Tom> 6. Handle duplicate class registration.

On reflection I think we don't need to make any change here.  Instead,
I think we can just require that a .so that is intended to override
part of the core must be linked with -Bsymbolic.  I think this will
avoid the duplicate registration problem altogether.

I've got java.endorsed.dirs basically working now.  I'm going to do
some testing tomorrow, but I'll send a preliminary patch to
java-patches for folks to look at.

Tom