Add emplace test

tl/optional.hpp

@@ -1258,6 +1258,7 @@ public:
 
     *this = nullopt;
     this->construct(std::forward<Args>(args)...);
+    return value();
   }
 
   /// \group emplace
@@ -1269,6 +1270,7 @@ public:
   emplace(std::initializer_list<U> il, Args &&... args) {
     *this = nullopt;
     this->construct(il, std::forward<Args>(args)...);
+    return value();    
   }
 
   /// Swaps this optional with the other.