The existing Reparent() implementation was wrong as it reparented spin control
subwindows under the new parent but left the main window itself under the old
one. Fix this by just not overriding Reparent() at all, the inherited version
works just fine for this control.
Closes#13849.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70432 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775