Add a basic TargetARM32 skeleton which knows nothing.

src/assembler_ia32.h

 //===- subzero/src/assembler_ia32.h - Assembler for x86-32 ------*- 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.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Assembler class for x86-32.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef SUBZERO_SRC_ASSEMBLER_IA32_H_
-#define SUBZERO_SRC_ASSEMBLER_IA32_H_
+#ifndef SUBZERO_SRC_ASSEMBLER_IA32_H
+#define SUBZERO_SRC_ASSEMBLER_IA32_H
 
 #include "IceConditionCodesX8632.h"
 #include "IceDefs.h"
 #include "IceOperand.h"
 #include "IceRegistersX8632.h"
 #include "IceTypes.h"
 #include "IceUtils.h"
 
 #include "assembler.h"
 
@@ skipping 842 matching lines @@
 
 inline void AssemblerX86::EmitFixup(AssemblerFixup *fixup) {
   buffer_.EmitFixup(fixup);
 }
 
 inline void AssemblerX86::EmitOperandSizeOverride() { EmitUint8(0x66); }
 
 } // end of namespace x86
 } // end of namespace Ice
 
-#endif // SUBZERO_SRC_ASSEMBLER_IA32_H_
+#endif // SUBZERO_SRC_ASSEMBLER_IA32_H