FutureTest.cpp - `explicit MoveCtorOnly(int)`

Summary: Add `explicit` to `MoveCtorOnly::MoveCtorOnly(int)` in FutureTest.cpp

Reviewed By: yfeldblum

Differential Revision: D8439496

fbshipit-source-id: 51217f186aa9b79d342a7be7f460d0a9c3f070c1

folly/futures/test/FutureTest.cpp

@@ -84,9 +84,9 @@ TEST(Future, makeFutureWithUnit) {
 
 TEST(Future, getRequiresOnlyMoveCtor) {
   struct MoveCtorOnly {
+    explicit MoveCtorOnly(int id) : id_(id) {}
     MoveCtorOnly(const MoveCtorOnly&) = delete;
     MoveCtorOnly(MoveCtorOnly&&) = default;
-    MoveCtorOnly(int id) : id_(id) {}
     void operator=(MoveCtorOnly const&) = delete;
     void operator=(MoveCtorOnly&&) = delete;
     int id_;