Add wxBitmap ctor from wxCursor to wxGTK and wxMSW.

Allow converting wxCursor to wxBitmap in order to draw it, for example.

Closes #15699.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77537 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/bitmap.h

@@ -97,6 +97,12 @@ public:
         CopyFromIcon(icon, transp);
     }
 
+    // Convert from wxCursor
+    wxEXPLICIT wxBitmap(const wxCursor& cursor)
+    {
+        (void)CopyFromCursor(cursor, wxBitmapTransparency_Auto);
+    }
+
     wxBitmap& operator=(const wxIcon& icon)
     {
         (void)CopyFromIcon(icon);