Try to prevent users from forgetting to include wx.rc from their resources.

Document that some of the standard cursors are defined in this file.

Also add a (hopefully) helpful assert if loading one of such cursors failed.

Closes #11424.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63276 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/gdicmn.h

@@ -58,7 +58,14 @@ enum wxPolygonFillMode
 };
 
 /**
-    Standard cursors. See wxCursor.
+    Standard cursors.
+
+    Notice that under wxMSW some of these cursors are defined in @c wx.rc file
+    and not by the system itself so you should include this file from your own
+    resource file (possibly creating a trivial resource file just containing a
+    single include line if you don't need it otherwise) to be able to use them.
+
+    See wxCursor.
 */
 enum wxStockCursor
 {