Add file header for GCEmptyBasicBlocks.cpp.

Author: rlavaee

llvm/lib/CodeGen/GCEmptyBasicBlocks.cpp

@@ -1,3 +1,16 @@
+//===-- GCEmptyBasicBlocks.cpp ----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the implementation of empty blocks garbage collection
+/// pass.
+///
+//===----------------------------------------------------------------------===//
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"