For UNO ABI reasons, these classes need to be CPPU_GCC_DLLPUBLIC_EXPORT (so
their RTTI symbols get exported), so they are careful to explicitly declare any
special member functions that would otherwise be declared implicitly, to mark
them CPPU_GCC_DLLPRIVATE.  But for LIBO_INTERNAL_ONLY, we always use
-fvisibility-inlines-hidden (except for MSVC, where it doesn't matter, as
CPPU_GCC_DLLPRIVATE expands to nothing there, either), so can leave those
functions implicitly declared, so not to prevent move ctor and move assign op
from being implicitly declared.

This covers cid#s 1371143, 1371162, 1371185, 1371189, 1371290, and 1371308.

Change-Id: I468088750a02f85a4790d956c37f4c30de03f00c