Patch: Serialization mods

[Tom Tromey]

Warren> FWIW, there's some code in defineclass.cc that verifies the
Warren> modifier associated with the object; I didn't add any checking
Warren> for STRICT in there, but that shouldn't hurt anything right
Warren> now.

If this change is correct, please make it now while we're aware of
it.  If we wait then it mutates into an obscure bug...

Warren> Libgcj does a much better job now of dealing with
Warren> serialVersionUID and most classes now match the JDK as they
Warren> should.

This is really cool.

Tom