xp-sp3: change grammer to support Qt5.6.3 for xp with sp3 system.

Protocol/Protocol.h

@@ -2,9 +2,10 @@
 #define PROTOCOL_H
 
 #include <QByteArray>
+#include <QMetaType>
 #include <QSharedPointer>
 #include <QString>
-#include <QMetaType>
+#include <functional>
 
 constexpr quint32 CHUNK_BUF_SIZE = 1 * 1024 * 1024;
 
@@ -54,5 +55,4 @@ public:
     static QByteArray PackBuffer(const QSharedPointer<FrameBuffer>& frame);
 };
 
-
 #endif   // PROTOCOL_H