[omniORB] Validity test

[Clarke Brunt]

> I wanted to know if omniORB offers a function to determine
> if a returned value points to a valid (non-null) memory address.

Enough said, probably. I meant to convey (in the original answer) that
barring a bug in the ORB there's no way that a null pointer can get passed
back from server to client, so you don't need to test for it. If the method
implementation tried to return a null pointer, then I'd expect the server
ORB to return an exception to the client instead, which the client ORB would
turn back into a C++ exception for you to catch.