The example immidiately destroys the QBluetoothServiceDiscoveryAgent
when the user selects a remote chat service from the remote selector
dialog. This may happen even when the scheduled QtConcurrent call
to runSdpScan() was still pending. The subsequent signal callback into
the deleted parent caused a crash.

Unfortunately QtConcurrent::run() returns a QFuture which does not
permit stopping the pending thread execution. Therefore the runSdpScan()
had to be rewritten using QProcess to properly destruct pending
calls.

Change-Id: I1ed5e147feb94a26240901a02d836056eddabbf6
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>