Move <optional> into include/experimental, and into the std::experimental namespace, since it's not part of C++14, but of an upcoming TS

llvm-svn: 194867

libcxx/test/utilities/optional/optional.object/optional.object.observe/value_const.fail.cpp

@@ -11,12 +11,14 @@
 
 // constexpr const T& optional<T>::value() const;
 
-#include <optional>
+#include <experimental/optional>
 #include <type_traits>
 #include <cassert>
 
 #if _LIBCPP_STD_VER > 11
 
+using std::experimental::optional;
+
 struct X
 {
     constexpr int test() const {return 3;}
@@ -29,7 +31,7 @@ int main()
 {
 #if _LIBCPP_STD_VER > 11
     {
-        constexpr std::optional<X> opt;
+        constexpr optional<X> opt;
         static_assert(opt.value().test() == 3, "");
     }
 #else