SKIEN, Norway—Anders Behring Breivik, the right-wing extremist who killed 77 people in bomb-and-gun massacres in Norway’s worst peacetime slaughter in 2011, appeared Tuesday before a court for a parole hearing. The Telemark District Court must rule whether Breivik is still so dangerous that society needs extra protection against him. and keep him behind bars A decade ago, the Norwegian mass killer was sentenced to 21 years in prison for the terrorist acts on the island of Utøya and in the government quarter in Oslo. It can be extended indefinitely. Under Norwegian law, Brevik, 42, is eligible to seek parole after serving the first 10 years of his term. Breivik, sporting a stubble beard and a two-piece suit, walked into the court room with white supremacist message pinned to his blazer, his bag and also held up a sign with the same message. He made Nazi salutes as he entered the …