Fix bug with removing items from menus with radio buttons in wxMSW.

Update the indices of the radio groups after removing an item from the menu.

See #14213.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76650 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775