fix doxygen brief in subzero header files

src/IceSwitchLowering.h

 //===- subzero/src/IceSwitchLowering.h - Switch lowering --------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// \brief The file contains helpers for switch lowering.
+/// \brief Helpers for switch lowering.
+///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICESWITCHLOWERING_H
 #define SUBZERO_SRC_ICESWITCHLOWERING_H
 
 #include "IceDefs.h"
 
 namespace Ice {
 
 class CaseCluster;
@@ skipping 76 matching lines @@
   IceString FuncName;
   SizeT Id;
   TargetList TargetOffsets;
 };
 
 using JumpTableDataList = std::vector<JumpTableData>;
 
 } // end of namespace Ice
 
 #endif //  SUBZERO_SRC_ICESWITCHLOWERING_H