BOSTON—Basketball Hall of Famer K.C. Jones, a 12-time NBA champion who was one of only seven players in history to win championships in college and the pros along with an Olympic gold medal, has died. He was 88. The Celtics said Jones’ family confirmed Friday that he died at an assistant living facility in Connecticut, where he had been receiving care for Alzheimer’s disease for the past several years. Earlier this year, two of Jones’ Celtics teammates died: John Thompson, 78, and Tom Heinsohn, 86. A point guard who excelled on defense, Jones joined with Bill Russell to lead San Francisco to back-to-back NCAA championships in 1955-56. The two also played on the U.S. team that won the Olympic gold medal at the 1956 Games in Melbourne. Jones reunited with Russell in Boston to win eight straight NBA titles from 1959-66. He retired in 1967 and began coaching, first in …