…ed_audio

Replace deprecated VBoxManage command

Got a compiler warning in vboxwrapper.cpp

vboxwrapper.cpp:684:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  684 |     for (int i=0; i<pVM->copy_to_shared.size(); ++i) {
      |                   ~^~~~~~~~~~~~~~~~~~~~~~~~~~~

Declared i as long unsigned int to avoid it.