fix doxygen brief in subzero header files

src/IceAssemblerARM32.h

 //===- subzero/src/IceAssemblerARM32.h - Assembler for ARM32 ----*- C++ -*-===//
 //
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
 //                        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 Assembler class for ARM32.
+/// \brief Declares the Assembler class for ARM32.
 ///
 /// Note: All references to ARM "section" documentation refers to the "ARM
 /// Architecture Reference Manual, ARMv7-A and ARMv7-R edition". See:
 /// http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0406c
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEASSEMBLERARM32_H
 #define SUBZERO_SRC_ICEASSEMBLERARM32_H
 
@@ skipping 362 matching lines @@
   // cccc=Cond, xxxxxxx<<21=Opcode, dddd=Rd, s=SetFlags, and
   // iiiiiiiiiiiiiiii=Imm16.
   void emitMovw(IValueT Opcode, IValueT Rd, IValueT Imm16, bool SetFlags,
                 CondARM32::Cond Cond);
 };
 
 } // end of namespace ARM32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEASSEMBLERARM32_H