fix doxygen brief in subzero header files

src/IceLoopAnalyzer.cpp

 //===- subzero/src/IceLoopAnalyzer.cpp - Loop Analysis --------------------===//
 //
 //                        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 loop analysis on the CFG.
+/// \brief Implements the loop analysis on the CFG.
 ///
 //===----------------------------------------------------------------------===//
 #include "IceLoopAnalyzer.h"
 
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 
 namespace Ice {
 
 void LoopAnalyzer::LoopNode::reset() {
@@ skipping 121 matching lines @@
       ++NumDeletedNodes;
       LoopStack.erase(It.base() - 1, LoopStack.end());
       break;
     }
   }
 
   return nullptr;
 }
 
 } // end of namespace Ice