Use wxSP_WRAP for generic wxTimePicker spin button.

This ensures that the spin button arrows are always enabled, as they should
be, even under wxGTK where wxSpinButton disables its arrows on its own if its
value reaches the end of its range and wxSP_WRAP is not used.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69289 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775