InstallManagerService: Clear notification on privileged install complete

* Without privileged extension, the install proceeds to user interaction
  which is where the notification is cleared.
* When the privileged extension is installed that doesn't happen,
  so the download notification doesn't get cleared

app/src/main/java/org/fdroid/fdroid/installer/InstallManagerService.java

@@ -335,6 +335,7 @@ public class InstallManagerService extends Service {
                         Apk apkComplete = removeFromActive(downloadUrl);
 
                         PackageManagerCompat.setInstaller(getPackageManager(), apkComplete.packageName);
+                        if (PrivilegedInstaller.isDefault(context)) cancelNotification(downloadUrl);
 
                         localBroadcastManager.unregisterReceiver(this);
                         break;