add IsOk() to all classes having Ok() method (patch 1570985)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41751 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/stream.h

@@ -266,7 +266,8 @@ public:
     wxCountingOutputStream();
 
     wxFileOffset GetLength() const;
-    bool Ok() const { return true; }
+    bool Ok() const { return IsOk(); }
+    bool IsOk() const { return true; }
 
 protected:
     virtual size_t OnSysWrite(const void *buffer, size_t size);