Fix creation of wxBitmap from monochrome wxIcon or wxCursor in wxMSW.

Don't suppose that we always have hbmColor because this is not true for
monochrome icons/cursors. Create our own bitmap in this case.

Closes #16512.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77517 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775