don't use annoying and unneeded in C++ casts of NULL to "T *" in all other files neither

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58227 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/os2/dataobj2.h

@@ -37,7 +37,7 @@ public:
     virtual bool SetData(size_t len, const void *buf);
 
 protected:
-    void Init() { m_pngData = (void *)NULL; m_pngSize = 0; }
+    void Init() { m_pngData = NULL; m_pngSize = 0; }
     void Clear() { free(m_pngData); }
     void ClearAll() { Clear(); Init(); }