Fix wxOSX compilation error after r75956.

wxScopedArray::get() needs to be explicitly called to access the array
contents as a pointer.

Closes #16015.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75974 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775