Get MSVC able to construct an Indestructible

Summary: It didn't like using `decltype(args)`, which wasn't really necessary as we already have it's type.

Reviewed By: yfeldblum

Differential Revision: D3623424

fbshipit-source-id: 994c23cbf486d427c6dd0fe4c6f768e51ea15ad1

folly/Indestructible.h

@@ -62,7 +62,7 @@ class Indestructible final {
  public:
   template <typename... Args>
   explicit constexpr Indestructible(Args&&... args) noexcept(
-      std::is_nothrow_constructible<T, decltype(args)...>::value)
+      std::is_nothrow_constructible<T, Args&&...>::value)
       : storage_(std::forward<Args>(args)...), inited_(true) {}
 
   ~Indestructible() = default;