Add --image-classes to dex2oat

Change-Id: Ia88f9d302e0f9cd72be2199ee46d212d99864c67
diff --git a/src/primitive.h b/src/primitive.h
index 240892f..5d41966 100644
--- a/src/primitive.h
+++ b/src/primitive.h
@@ -116,6 +116,8 @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(Primitive);
 };
 
+std::ostream& operator<<(std::ostream& os, const Primitive::Type& state);
+
 }  // namespace art
 
 #endif  // ART_SRC_PRIMITIVE_H_