Compilation fix to wxScopedArray use.

The ctor taking the number of elements doesn't exist in 3.0, don't use it to
fix compilation after the changes of r76124.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76137 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775