compilation fix: wxUString uses it's own wxCharTypeBuffer<T> specializations and so needs NullData definitions for them too

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@55050 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/ustring.cpp

@@ -545,4 +545,16 @@ wxU16CharBuffer wxUString::utf16_str() const
     
     return result;    
 }
-    
+
+
+#if SIZEOF_WCHAR_T != 2
+template<>
+wxCharTypeBuffer<wxChar16>::Data
+wxCharTypeBuffer<wxChar16>::NullData(NULL);
+#endif
+
+#if SIZEOF_WCHAR_T != 4
+template<>
+wxCharTypeBuffer<wxChar32>::Data
+wxCharTypeBuffer<wxChar32>::NullData(NULL);
+#endif