Biopics about American war heroes are a Hollywood tradition going all the way back to Gary Cooper starring as the legendary World War I sharpshooter “Sergeant York” and World War II’s highly decorated Audie Murphy playing himself in “To Hell and Back.” “American Sniper” is squarely in that mold, but because it’s directed by Clint Eastwood something else is going on as well. Taken from the autobiography of the same name, “American Sniper” stars Bradley Cooper as Chris Kyle, the Navy SEAL whose 160 confirmed kills during four tours of duty in Iraq made him the deadliest sniper in U.S. military history.