Remove pthread dependency

include/ftxui/component/receiver.hpp

@@ -14,6 +14,8 @@
 
 namespace ftxui {
 
+// Deprecated
+//
 // Usage:
 //
 // Initialization:
@@ -39,17 +41,24 @@ namespace ftxui {
 // Receiver::Receive() returns true when there are no more senders.
 
 // clang-format off
+// Deprecated:
 template<class T> class SenderImpl;
+// Deprecated:
 template<class T> class ReceiverImpl;
+// Deprecated:
 
+// Deprecated:
 template<class T> using Sender = std::unique_ptr<SenderImpl<T>>;
+// Deprecated:
 template<class T> using Receiver = std::unique_ptr<ReceiverImpl<T>>;
+// Deprecated:
 template<class T> Receiver<T> MakeReceiver();
 // clang-format on
 
 // ---- Implementation part ----
 
 template <class T>
+// Deprecated:
 class SenderImpl {
  public:
   SenderImpl(const SenderImpl&) = delete;