RemoteVstPlugin: allocate buffer for chunk on heap rather than stack

It's not a good idea to allocate the buffer for VST chunk data on the
stack as chunks might become quite big (several megabytes) and thus
could cause a stack overflow. Fix this by using new/delete.
(cherry picked from commit 5f241e6374)

plugins/vst_base/remote_vst_plugin.cpp

@@ -813,7 +813,7 @@ void RemoteVstPlugin::saveChunkToFile( const std::string & _file )
 
 void RemoteVstPlugin::loadChunkFromFile( const std::string & _file, int _len )
 {
-	char buf[_len];
+	char * buf = NULL;
 
 	void * chunk = NULL;
 	// various plugins need this in order to not crash when setting
@@ -823,7 +823,8 @@ void RemoteVstPlugin::loadChunkFromFile( const std::string & _file, int _len )
 	// allocated buffer big enough?
 	if( _len > actualLen )
 	{
-		// no, manually try our local buffer
+		// no, then manually allocate a buffer
+		buf = new char[_len];
 		chunk = buf;
 	}
 
@@ -831,6 +832,8 @@ void RemoteVstPlugin::loadChunkFromFile( const std::string & _file, int _len )
 	read( fd, chunk, _len );
 	close( fd );
 	pluginDispatch( 24, 0, _len, chunk );
+
+	delete[] buf;
 }