fix doxygen brief in subzero header files

src/IceInst.cpp

 //===- subzero/src/IceInst.cpp - High-level instruction implementation ----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
-/// This file implements the Inst class, primarily the various subclass
+/// \brief Implements the Inst class, primarily the various subclass
 /// constructors and dump routines.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "IceInst.h"
 
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceInstVarIter.h"
 #include "IceLiveness.h"
@@ skipping 936 matching lines @@
     // upper 32 bits of rax. We need to recognize and preserve these.
     return true;
   }
   if (!Dest->hasReg() && !SrcVar->hasReg() &&
       Dest->getStackOffset() == SrcVar->getStackOffset())
     return true;
   return false;
 }
 
 } // end of namespace Ice