Use Cmd-click, not Apply-click, to select items in wxVListBox.

Using Apple key here under Mac was unexpected, we should use Cmd which
corresponds to Ctrl used under the other platforms and which is already mapped
to it by wxKeyboardState::ControlDown().

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78303 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775