fix doxygen brief in subzero header files

src/IceFixups.h

 //===- subzero/src/IceFixups.h - Assembler fixup kinds ----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// This file declares generic fixup types.
+/// \brief Declares generic fixup types.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEFIXUPS_H
 #define SUBZERO_SRC_ICEFIXUPS_H
 
 #include "IceDefs.h"
 
 namespace Ice {
 
@@ skipping 59 matching lines @@
   const std::string Message;
   const size_t NumBytes;
 };
 
 using FixupList = std::vector<AssemblerFixup>;
 using FixupRefList = std::vector<AssemblerFixup *>;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEFIXUPS_H