[presubmit] Enable readability/namespace linter checking.

src/regexp/ppc/regexp-macro-assembler-ppc.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_REGEXP_PPC_REGEXP_MACRO_ASSEMBLER_PPC_H_
 #define V8_REGEXP_PPC_REGEXP_MACRO_ASSEMBLER_PPC_H_
 
 #include "src/macro-assembler.h"
 #include "src/ppc/assembler-ppc.h"
 #include "src/ppc/frames-ppc.h"
@@ skipping 190 matching lines @@
   Label check_preempt_label_;
   Label stack_overflow_label_;
   Label internal_failure_label_;
 };
 
 // Set of non-volatile registers saved/restored by generated regexp code.
 const RegList kRegExpCalleeSaved =
     1 << 25 | 1 << 26 | 1 << 27 | 1 << 28 | 1 << 29 | 1 << 30 | 1 << 31;
 
 #endif  // V8_INTERPRETED_REGEXP
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_REGEXP_PPC_REGEXP_MACRO_ASSEMBLER_PPC_H_