SAN FRANCISCO (Reuters) - Intel Corp forecast current-quarter revenue that was slightly below expectations as the personal computer industry grapples with falling sales and a shift toward tablets and smartphones. PC makers are struggling to stop a decline in sales as consumers hold off on buying new laptops in favor of spending on more nimble mobile gadgets. Microsoft Corp's long-awaited launch of Windows 8 in October brought touchscreen features to laptops but failed to spark a resurgence in sales that Intel and many PC manufacturers had hoped for. ...