CORBA23 — Clarify meaning of no IDL initializers

Summary: Section 3.8.1.5 on page 24 does not make it clear what it means to
have no initializers for an IDL valuetype. The decision of the OBV
designers, which is reflected in the C++ and Java language mappings,
was that this means there is no portable way to create an instance
of the value type. This should be clearly stated in the definition of
IDL semantics for valuetypes, not deduced from the language mappings.

Fix it