BRUSSELS/FRANKFURT/LONDON (Reuters) -A cyberattack at a provider of check-in and boarding systems disrupted operations on Saturday at several major European airports including London's Heathrow, the continent's busiest, causing flight delays and cancellations. The disruption is the latest in a string of hacks targeting governments and companies across the world, hitting sectors from healthcare and defence to retail and autos. A recent breach at luxury carmaker Jaguar Land Rover brought its production to a halt.