Support callee-save registers on ARM.

Change-Id: I7c519b7a828c9891b1141a8e51e12d6a8bc84118
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 46accfd..dd69e4d 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -245,6 +245,8 @@
     return type == Primitive::kPrimDouble || type == Primitive::kPrimLong;
   }
 
+  void ComputeSpillMask() OVERRIDE;
+
  private:
   // Labels for each block that will be compiled.
   GrowableArray<Label> block_labels_;