No real changes, just inline wxSuspendStyleEvents.

wxSuspendStyleEvents helper class was used in one place only and the code is
more clear if its ctor and dtor are inlined directly into DoApplyWidgetStyle()
itself instead of being located far away from it.

Also, we only need to suppress the events for top level windows so don't
bother doing anything at all when changing styles for m_widget and not m_wxwindow.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62285 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775