[gardening] Add missing swift comment header to file.

Author: gottesmm

lib/SILOptimizer/Utils/CheckedCastBrJumpThreading.cpp

@@ -1,3 +1,15 @@
+//===--- CheckedCastBrJumpThreading.cpp -----------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
 #define DEBUG_TYPE "sil-simplify-cfg"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"