Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
  -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
  llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
diff --git a/llvm/lib/Transforms/Hello/Hello.cpp b/llvm/lib/Transforms/Hello/Hello.cpp
index 29b9bb8..f90aafc 100644
--- a/llvm/lib/Transforms/Hello/Hello.cpp
+++ b/llvm/lib/Transforms/Hello/Hello.cpp
@@ -35,7 +35,7 @@
       return false;
     }
   };
-}
+} // namespace
 
 char Hello::ID = 0;
 static RegisterPass<Hello> X("hello", "Hello World Pass");
@@ -58,7 +58,7 @@
       AU.setPreservesAll();
     }
   };
-}
+} // namespace
 
 char Hello2::ID = 0;
 static RegisterPass<Hello2>