Refactor code for unresolved field entrypoint.

- Do macro magic to avoid source code duplication.
- Do not fetch the referrer from the assembly, but
  from the C entrypoint instead.

Test: test-art-host test-art-target

Change-Id: Ib139c94bc8f74686640cad538ba75dc56fa00e1d
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index 9eb9765..285a3fe 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -110,7 +110,9 @@
   }
   Location GetSetValueLocation(Primitive::Type type, bool is_instance) const OVERRIDE {
     return Primitive::Is64BitType(type)
-        ? Location::RegisterPairLocation(EDX, EBX)
+        ? (is_instance
+            ? Location::RegisterPairLocation(EDX, EBX)
+            : Location::RegisterPairLocation(ECX, EDX))
         : (is_instance
             ? Location::RegisterLocation(EDX)
             : Location::RegisterLocation(ECX));