[clang-tidy] Cleaning namespaces to be more consistant across checkers.

Summary:
The goal of the patch is to bring checkers in their appropriate namespace.
This path doesn't change any behavior.

Reviewers: alexfh

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D19811

llvm-svn: 268264
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.h b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.h
index 1caf28c..b83475c 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.h
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.h
@@ -15,6 +15,7 @@
 
 namespace clang {
 namespace tidy {
+namespace cppcoreguidelines {
 
 /// This checks that all array subscriptions on static arrays and std::arrays
 /// have a constant index and are within bounds
@@ -34,6 +35,7 @@
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
 };
 
+} // namespace cppcoreguidelines
 } // namespace tidy
 } // namespace clang