silence MSVC8 warnings through pragmas, fixes #2296

[SVN r48821]

include/boost/concept_check.hpp

@@ -171,6 +171,11 @@ namespace boost
     TT b;
   };
 
+#if (defined _MSC_VER)
+# pragma warning( push )
+# pragma warning( disable : 4510 ) // default constructor could not be generated
+# pragma warning( disable : 4610 ) // object 'class' can never be instantiated - user-defined constructor required
+#endif
   // The SGI STL version of Assignable requires copy constructor and operator=
   BOOST_concept(SGIAssignable,(TT))
   {
@@ -192,6 +197,9 @@ namespace boost
     }
     TT a;
   };
+#if (defined _MSC_VER)
+# pragma warning( pop )
+#endif
 
   BOOST_concept(Convertible,(X)(Y))
   {