RemoteVstPlugin: don't process MIDI events in GUI thread

Don't process MIDI events in GUI thread as this might corrupt MIDI
event array if both GUI and processing thread access it. Fixes
possible crashes.

Signed-off-by: Tobias Doerffel <tobias.doerffel@gmail.com>
(cherry picked from commit e7ab8e5670)

plugins/vst_base/remote_vst_plugin.cpp

@@ -1219,7 +1219,7 @@ DWORD WINAPI RemoteVstPlugin::processingThread( LPVOID _param )
 	remotePluginClient::message m;
 	while( ( m = _this->receiveMessage() ).id != IdQuit )
         {
-		if( m.id == IdStartProcessing )
+		if( m.id == IdStartProcessing || m.id == IdMidiEvent )
 		{
 			_this->processMessage( m );
 		}