[presubmit] Enable readability/namespace linter checking.

src/ppc/simulator-ppc.h

Index: src/ppc/simulator-ppc.h
diff --git a/src/ppc/simulator-ppc.h b/src/ppc/simulator-ppc.h
index 042b2ada2c6edf51d9489870c36395cf52f0a81c..0df30da9e91efbe8dd5c22de53be79beee6d5dad 100644
--- a/src/ppc/simulator-ppc.h
+++ b/src/ppc/simulator-ppc.h
@@ -54,8 +54,8 @@ class SimulatorStack : public v8::internal::AllStatic {
 
   static inline void UnregisterCTryCatch() {}
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #else  // !defined(USE_SIMULATOR)
 // Running with a simulator.
@@ -422,8 +422,8 @@ class SimulatorStack : public v8::internal::AllStatic {
     Simulator::current(Isolate::Current())->PopAddress();
   }
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // !defined(USE_SIMULATOR)
 #endif  // V8_PPC_SIMULATOR_PPC_H_