Fix cpplint build/namespaces issues

Change-Id: I19c68703270c1482d6c6aad8cdf97d3d2924360a
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index 7fd1a7c..f395428 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -52,7 +52,14 @@
 #include "UniquePtr.h"
 #include "utils.h"
 
-using namespace art::mirror;
+using ::art::mirror::AbstractMethod;
+using ::art::mirror::Class;
+using ::art::mirror::DexCache;
+using ::art::mirror::EntryPointFromInterpreter;
+using ::art::mirror::Field;
+using ::art::mirror::Object;
+using ::art::mirror::ObjectArray;
+using ::art::mirror::String;
 
 namespace art {