InstrumentTrack: do not try to load "libconnection.so" in compat code

In compat code of InstrumentTrack::loadTrackSpecificSettings() also
check for nodeName being equal to ControllerConnection::classNodeName().
This avoids trying to load the non-existing instrument "connection".
In master branch this has been fixed ugly in commit 22c877d4 before,
however implement a cleaner solution which is also suitable for
backporting.

Closes #3021259.
(cherry picked from commit 65311ef2b4)

include/ControllerConnection.h

@@ -5,6 +5,7 @@
  *              loading project
  *
  * Copyright (c) 2008 Paul Giblock <pgllama/at/gmail.com>
+ * Copyright (c) 2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -80,7 +81,17 @@ public:
 
 	virtual void saveSettings( QDomDocument & _doc, QDomElement & _this );
 	virtual void loadSettings( const QDomElement & _this );
-	virtual QString nodeName() const;
+
+	static inline const QString classNodeName()
+	{
+		return "connection";
+	}
+
+	virtual QString nodeName() const
+	{
+		return classNodeName();
+	}
+
 
 public slots:
 	void deleteConnection();

src/core/ControllerConnection.cpp

@@ -3,6 +3,7 @@
  *            which handles the link between AutomatableModels and controllers
  *
  * Copyright (c) 2008 Paul Giblock <drfaygo/at/gmail.com>
+ * Copyright (c) 2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -208,12 +209,6 @@ void ControllerConnection::deleteConnection()
 	delete this;
 }
 
-QString ControllerConnection::nodeName() const
-{
-	return( "connection" );
-}
-
 
 #include "moc_ControllerConnection.cxx"
 
-

src/tracks/InstrumentTrack.cpp

@@ -2,7 +2,7 @@
  * InstrumentTrack.cpp - implementation of instrument-track-class
  *                        (window + data-structures)
  *
- * Copyright (c) 2004-2009 Tobias Doerffel <tobydox/at/users.sourceforge.net>
+ * Copyright (c) 2004-2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -43,6 +43,7 @@
 #include "automation_pattern.h"
 #include "bb_track.h"
 #include "config_mgr.h"
+#include "ControllerConnection.h"
 #include "debug.h"
 #include "EffectChain.h"
 #include "EffectRackView.h"
@@ -812,8 +813,8 @@ void InstrumentTrack::loadTrackSpecificSettings( const QDomElement & _this )
 			// compat code - if node-name doesn't match any known
 			// one, we assume that it is an instrument-plugin
 			// which we'll try to load
-			else if( automationPattern::classNodeName() !=
-							node.nodeName() &&
+			else if( automationPattern::classNodeName() != node.nodeName() &&
+					ControllerConnection::classNodeName() != node.nodeName() &&
 					!node.toElement().hasAttribute( "id" ) )
 			{
 				delete m_instrument;