servercontext wait for transport worker threads to finish

doing this through Transport::close()
causes deadlock in client code due to locking.
So make this an extra step.

src/remote/codec.cpp

@@ -1001,9 +1001,7 @@ bool AbstractCodec::directDeserialize(ByteBuffer *existingBuffer, char* deserial
 
 BlockingTCPTransportCodec::~BlockingTCPTransportCodec()
 {
-    assert(!_isOpen.get());
-    _sendThread.exitWait();
-    _readThread.exitWait();
+    waitJoin();
 }
 
 void BlockingTCPTransportCodec::readPollOne() {
@@ -1035,6 +1033,13 @@ void BlockingTCPTransportCodec::close() {
     }
 }
 
+void BlockingTCPTransportCodec::waitJoin()
+{
+    assert(!_isOpen.get());
+    _sendThread.exitWait();
+    _readThread.exitWait();
+}
+
 void BlockingTCPTransportCodec::internalClose(bool /*force*/)
 {
     this->internalDestroy();

src/remote/pv/codec.h

@@ -317,6 +317,7 @@ public:
     virtual void scheduleSend() OVERRIDE FINAL {}
     virtual void sendCompleted() OVERRIDE FINAL {}
     virtual void close() OVERRIDE FINAL;
+    virtual void waitJoin() OVERRIDE FINAL;
     virtual bool terminated() OVERRIDE FINAL;
     virtual bool isOpen() OVERRIDE FINAL;
     void start();

src/remote/pv/remote.h

@@ -287,6 +287,9 @@ public:
      */
     virtual void close() = 0;
 
+    //! Call after close() to wait for any worker threads to exit
+    virtual void waitJoin() {}
+
     /**
      * Check connection status.
      * @return <code>true</code> if connected.

src/server/serverContext.cpp

@@ -375,6 +375,7 @@ void ServerContextImpl::destroyAllTransports()
     for (size_t i = 0; i < size; i++)
     {
         const Transport::shared_pointer& transport = transports[i];
+        transport->waitJoin();
         if(!transport.unique())
             LOG(logLevelError, "Closed transport %s still has use_count=%u",
                 transport->getRemoteName().c_str(),