Add a basic TargetARM32 skeleton which knows nothing.

src/IceInstARM32.h

Index: src/IceInstARM32.h
diff --git a/src/IceInstARM32.h b/src/IceInstARM32.h
new file mode 100644
index 0000000000000000000000000000000000000000..1c7d346bc92e8c9608fc511152c360e3071b50f7
--- /dev/null
+++ b/src/IceInstARM32.h
@@ -0,0 +1,28 @@
+//===- subzero/src/IceInstARM32.h - ARM32 machine instructions --*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the InstARM32 and OperandARM32 classes and
+// their subclasses.  This represents the machine instructions and
+// operands used for ARM32 code selection.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICEINSTARM32_H
+#define SUBZERO_SRC_ICEINSTARM32_H
+
+#include "IceDefs.h"
+
+namespace Ice {
+
+class TargetARM32;
+// Fill this in.
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICEINSTARM32_H