The old code which simply used PBM_SETPOS after setting PBS_MARQUEE style often worked but sometimes apparently didn't, so switch to the officially sanctioned PBM_SETMARQUEE to implement this. Also make wxGauge::SetDeterminateMode() and SetIndeterminateMode() methods private as they are not part of the public class API. Closes #11357. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64648 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775