Minor void return fixes (MSVC 6 on -W4, g++ 2.95.3)

[SVN r11706]

mem_fn_stdcall_test.cpp

@@ -20,8 +20,18 @@
 
 #include <boost/mem_fn.hpp>
 #include <boost/smart_ptr.hpp>
+
+#if defined(BOOST_MSVC) && (BOOST_MSVC < 1300)
+#pragma warning(push, 3)
+#endif
+
 #include <iostream>
 
+#if defined(BOOST_MSVC) && (BOOST_MSVC < 1300)
+#pragma warning(pop)
+#endif
+
+
 struct X
 {
     mutable unsigned int hash;