(Reuters) -Four major British housebuilders have signed a government-backed safety pledge to remove flammable roof coverings from buildings which came into focus after the deadly Grenfell Tower fire in London. The country’s second-largest and third-largest homebuilders, Persimmon and Taylor Wimpey, said on Tuesday they had signed the “Developer Pledge” setting out commitments for coverings called cladding in high-rise buildings. Fire safety of buildings in Britain came into prominence after the 2017 blaze killed more than 70 people and revealed the widespread use of cheap flammable cladding on…