BackoffTimeout disallow copy, move, default ctor

Summary:
BackoffTimeout disallow copy construction, copy assignment, move
construction, move assignment, and default construction.

Closes https://github.com/facebook/folly/pull/146

Test Plan: runtests

Reviewed By: ldbrandy@fb.com

Subscribers: lins, anca, folly-diffs@, yfeldblum

FB internal diff: D1912521

Signature: t1:1912521:1426268413:6edb2d8203d1efd1e825816f03be115ac46e55ca

folly/io/async/AsyncServerSocket.cpp

@@ -116,9 +116,10 @@ void AsyncServerSocket::RemoteAcceptor::messageAvailable(
  */
 class AsyncServerSocket::BackoffTimeout : public AsyncTimeout {
  public:
+  // Disallow copy, move, and default constructors.
+  BackoffTimeout(BackoffTimeout&&) = delete;
   BackoffTimeout(AsyncServerSocket* socket)
-    : AsyncTimeout(socket->getEventBase()),
-      socket_(socket) {}
+      : AsyncTimeout(socket->getEventBase()), socket_(socket) {}
 
   virtual void timeoutExpired() noexcept {
     socket_->backoffTimeoutExpired();