By John Revill ZURICH (Reuters) – Siemens is buying U.S. tech company Brightly Software from private equity owner Clearlake Capital for $1.58 billion, the German engineering group said on Monday, its latest move to broaden its software credentials and grow faster than rivals. Siemens Smart Infrastructure, which offers digital systems to manage buildings’ security and energy consumption, is buying Brightly to expand its offering in the area of “software as a service” (SAAS). Brightly, based in North Carolina, makes cloud-based software that collects data from sensors installed in buildings and …