fix doxygen brief in subzero header files

src/IceGlobalInits.cpp

 //===- subzero/src/IceGlobalInits.cpp - Global declarations ---------------===//
 //
 //                        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 notion of function declarations, global variable
+/// \brief Implements the notion of function declarations, global variable
 /// declarations, and the corresponding variable initializers in Subzero.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "IceGlobalInits.h"
 
 #include "IceDefs.h"
 #include "IceGlobalContext.h"
 #include "IceTypes.h"
 #include "llvm/ADT/STLExtras.h"
@@ skipping 174 matching lines @@
   dumpType(Stream);
   Stream << ")";
   if (Offset != 0) {
     Stream << ", ";
     dumpType(Stream);
     Stream << " " << Offset << ")";
   }
 }
 
 } // end of namespace Ice