Make RPC message constructor actually move (pytorch#33440)

Summary:
Pull Request resolved: pytorch#33440

The constructors make a copy without `std::move` in the initializer list.

Test Plan:
Confirmed manually that without this change, the `data()` pointer of
the vector changes. With this change it does not, as intended.

Reviewed By: mrshenli

Differential Revision: D19948685

fbshipit-source-id: ee4f22e29894b858ad86068722dc2f4651987517

torch/csrc/distributed/rpc/message.cpp

@@ -10,14 +10,17 @@ Message::Message(
     std::vector<char>&& payload,
     std::vector<torch::Tensor>&& tensors,
     MessageType type)
-    : payload_(payload), tensors_(tensors), type_(type) {}
+    : payload_(std::move(payload)), tensors_(std::move(tensors)), type_(type) {}
 
 Message::Message(
     std::vector<char>&& payload,
     std::vector<torch::Tensor>&& tensors,
     MessageType type,
     int64_t id)
-    : payload_(payload), tensors_(tensors), type_(type), id_(id) {}
+    : payload_(std::move(payload)),
+      tensors_(std::move(tensors)),
+      type_(type),
+      id_(id) {}
 
 Message::Message(const Message& other) = default;