Fix PR libgcj/2237:
* java/io/ObjectStreamClass.java (setClass): Calculate
serialVersionUID for local class and compare it against the UID
from the Object Stream. Throw InvalidClassException upon mismatch.
(setUID): Renamed to...
(getClassUID): this. Return the calculated class UID rather than
setting uid field directly.
(getDefinedSUID): Removed.
* java/io/ObjectInputStream.java (resolveClass): Use the
three-argument Class.forName().
* java/io/InvalidClassException (toString): Don't include classname in
result if it is null.
From-SVN: r41567
