Fusion: silenced a couple of MSVC warnings created during Spirit test runs

[SVN r57502]

include/boost/fusion/sequence/io/detail/manip.hpp

@@ -146,6 +146,10 @@ namespace boost { namespace fusion
             }
 
             Stream& stream;
+
+        private:
+            // silence MSVC warning C4512: assignment operator could not be generated
+            string_ios_manip& operator= (string_ios_manip const&);
         };
 
     } // detail