Sf2Player: disable per-note-panning support for the time being

The per-note-panning support is broken (not sure whether this is a bug
in FluidSynth or our code) and leads to improperly panned sounds all
the time - even with all notes being panned to center. Thus disable it
until we have a proper fix for it.
(cherry picked from commit 22489ae321)

plugins/sf2_player/sf2_player.cpp

@@ -631,6 +631,7 @@ void sf2Instrument::playNote( notePlayHandle * _n, sampleFrame * )
 
 	SF2PluginData * pluginData = static_cast<SF2PluginData *>(
 							_n->m_pluginData );
+#ifdef SOMEONE_FIXED_PER_NOTE_PANNING
 	if( pluginData->fluidVoice &&
 			pluginData->lastPanning != _n->getPanning() )
 	{
@@ -645,6 +646,7 @@ void sf2Instrument::playNote( notePlayHandle * _n, sampleFrame * )
 
 		pluginData->lastPanning = _n->getPanning();
 	}
+#endif
 
 	const float currentVelocity = _n->volumeLevel( tfp ) * 127;
 	if( pluginData->fluidVoice &&