Codechange: Replace custom thread code with C++11 thread objects.

We assume a conforming C++11 compiler environment that has a valid <thread>-header.
Failure to run a real thread is handled gracefully.

src/network/core/tcp.h

@@ -63,7 +63,6 @@ public:
  */
 class TCPConnecter {
 private:
-	class ThreadObject *thread; ///< Thread used to create the TCP connection
 	bool connected;             ///< Whether we succeeded in making the connection
 	bool aborted;               ///< Whether we bailed out (i.e. connection making failed)
 	bool killed;                ///< Whether we got killed
@@ -71,7 +70,7 @@ private:
 
 	void Connect();
 
-	static void ThreadEntry(void *param);
+	static void ThreadEntry(TCPConnecter *param);
 
 protected:
 	/** Address we're connecting to */