...as required by clang-cl:

> [build CXX] avmedia/source/framework/modeltools.cxx
> In file included from C:/lo64/core/avmedia/source/framework/modeltools.cxx:29:
> In file included from C:/lo64/core/external/boost/include\boost/exception/diagnostic_information.hpp:23:
> In file included from C:/lo64/core/workdir/UnpackedTarball/boost\boost/exception/diagnostic_information.hpp:17:
> C:/lo64/core/workdir/UnpackedTarball/boost\boost/exception/info.hpp(103,13):  error: 'boost::exception_detail::error_info_container_impl' has virtual functions but non-virtual destructor [-Werror,-Wnon-virtual-dtor]
>             ~error_info_container_impl() throw()
>             ^
> C:/lo64/core/workdir/UnpackedTarball/boost\boost/exception/info.hpp(172,21):  error: delete called on non-final 'boost::exception_detail::error_info_container_impl' that has virtual functions but non-virtual destructor [-Werror,-Wdelete-non-virtual-dtor]
>                     delete this;
>                     ^
> 2 errors generated.

Change-Id: I026f7e72d027becb68ac9118616ed6d8f2ecbf80
Reviewed-on: https://gerrit.libreoffice.org/41225Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>