EASTHAM — Resting beneath the National Seashore’s Salt Pond Visitor Center is what used to be the ninth hole of the Cedar Bank Links golf course. The Eastham Town Hall sits atop the 12th hole, and the other 16 have been buried under the dunes and marshes rimming the pond and the Nauset Inlet. Willow Shire, who owns a place neighboring the old, white-chimneyed clubhouse, points out traces of bunkers, now carpeted by grasses and shrubs. The concrete rollers that once smoothed the greens remain in the high grass.