Windows Phone may be a dead man walking, but the PC giants still cling to the dream of a unified platform spanning traditional and mobile devices. Hewlett-Packard, whose record in mobile operating systems has been particularly disastrous – especially its shortlived acquisition of Palm’s webOS – is following Dell in sidelining Android and focusing on Windows 10 Mobile for smartphones and tablets. This is the latest example of the dilemma which has faced the PC industry – from Intel and Microsoft to the PC manufacturers – ever since the mobile device started to usurp the role of the desktop and notebook. Android has clearly won the handset OS wars, but it is dominated by cellphone players. The PC vendors have…