GIOP1.2 orb implementation does not pass custom value types properly.

These include any Serializables which have writeObject methods such as
Hashtables, as well as any IDL valuetypes declared as such.
********************************************************************************

###@###.### 2001-11-13

Fix verified OK:
- using build: j2sdk-1_4_0-rc-bin-b85-solsparc-07_nov_2001
- by running tests at: tests/product/giop/customMarshalling
tests/product/giop/valuetypes
********************************************************************************