Add movw and movt support for ARMv7. This includes some code from...

src/arm/constants-arm.h

Index: src/arm/constants-arm.h
===================================================================
--- src/arm/constants-arm.h	(revision 4906)
+++ src/arm/constants-arm.h	(working copy)
@@ -284,6 +284,9 @@
     // with immediate
   inline int RotateField() const { return Bits(11, 8); }
   inline int Immed8Field() const { return Bits(7, 0); }
+  inline int Immed4Field() const { return Bits(19, 16); }
+  inline int ImmedMovwMovtField() const {
+      return Immed4Field() << 12 | Offset12Field(); }
 
   // Fields used in Load/Store instructions
   inline int PUField() const { return Bits(24, 23); }