Fixed is_same<T,U> so it would work with T == void or U == void

Suppressed some warnings in from_not_void_conversion<> for MSVC
Fixed a spelling error


[SVN r8665]

libs/type_traits

@@ -1 +1 @@
-Subproject commit bb21fc7f1d27ee84c67c04c11b2c85a022a0d6a4
+Subproject commit a394b441500bfd170fcaf9671874a14a7f089653