Disable Bluetooth option from GUI if SSRF_CUSTOM_SERIAL is undefined

The Bluetooth implementation doesn't work if SSRF_CUSTOM_SERIAL
is undefined. Therefore it is a good idea to remove it from
the UI if the libdivecomputer version is wrong.

Signed-off-by: Claudiu Olteanu <olteanu.claudiu@ymail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/downloadfromdivecomputer.cpp

@@ -100,7 +100,7 @@ DownloadFromDCWidget::DownloadFromDCWidget(QWidget *parent, Qt::WindowFlags f) :
 	ui.downloadCancelRetryButton->setEnabled(true);
 	ui.downloadCancelRetryButton->setText(tr("Download"));
 
-#if defined(BT_SUPPORT)
+#if defined(BT_SUPPORT) && defined(SSRF_CUSTOM_SERIAL)
 	ui.bluetoothMode->setText(tr("Choose Bluetooth download mode"));
 	ui.bluetoothMode->setChecked(default_dive_computer_download_mode == DC_TRANSPORT_BLUETOOTH);
 	btDeviceSelectionDialog = 0;