Make css::uno::Reference upcast ctor LIBO_INTERNAL_ONLY

It looks like an oversight that 904b3d1fceee5827076758ed2a81f80cb73493ca "Up-
cast conversion constructor for css::uno::Reference" added it also for external
code.  Making it LIBO_INTERNAL_ONLY allows to remove workarounds for old MSVC,
and may allow to simplify the code further in the future.  (Though using
std::is_base_of, as suggested in the comment, is not easily possible, as it
would cause errors like

> include/c++/v1/type_traits:1726:59: error: incomplete type 'com::sun::star::lang::XMultiServiceFactory' used in type trait expression
>     : public integral_constant<bool, __is_base_of(_Bp, _Dp)> {};
>                                                           ^
> include/c++/v1/type_traits:1731:7: note: in instantiation of template class 'std::__1::is_base_of<com::sun::star::beans::XPropertySet, com::sun::star::lang::XMultiServiceFactory>' requested here
>     = is_base_of<_Bp, _Dp>::value;
>       ^
> include/com/sun/star/uno/Reference.h:277:18: note: in instantiation of variable template specialization 'std::__1::is_base_of_v<com::sun::star::beans::XPropertySet, com::sun::star::lang::XMultiServiceFactory>' requested here
>             std::is_base_of_v<interface_type, derived_type>
>                  ^
> ucbhelper/source/provider/getcomponentcontext.cxx:34:9: note: while substituting deduced template arguments into function template 'Reference' [with derived_type = com::sun::star::lang::XMultiServiceFactory]
>         css::uno::Reference< css::beans::XPropertySet >(
>         ^
> include/ucbhelper/getcomponentcontext.hxx:29:28: note: forward declaration of 'com::sun::star::lang::XMultiServiceFactory'
>     namespace lang { class XMultiServiceFactory; }
>                            ^

with incomplete types.)

Change-Id: I6da3395df904797cec83c1f6ab24b386527d4cea
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/92802
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

0 files changed, 0 insertions, 0 deletions