Add copy operator to QBluetoothHostInfo.

The QBluetoothSocket unit test was sometimes failing because of it.

Change-Id: I6071902e1aaa9e1138f071b7f2ce2a8ccb436789
Reviewed-by: Nedim Hadzic <nedimhadzija@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>