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

The patch is generated using this command:

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

To reduce churn, not touching namespaces spanning less than 10 lines.

llvm-svn: 240270
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index 9947fad..f6a5a06 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -1895,7 +1895,7 @@
   }
 };
 
-}
+} // namespace
 
 Sema::ObjCMessageKind Sema::getObjCMessageKind(Scope *S,
                                                IdentifierInfo *Name,
@@ -3184,7 +3184,7 @@
       }
     }
   };
-}
+} // namespace
 
 bool Sema::isKnownName(StringRef name) {
   if (name.empty())