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/AST/DeclObjC.cpp b/clang/lib/AST/DeclObjC.cpp
index a1600cb..c2c590f 100644
--- a/clang/lib/AST/DeclObjC.cpp
+++ b/clang/lib/AST/DeclObjC.cpp
@@ -1259,7 +1259,7 @@
                  const SynthesizeIvarChunk &RHS) {
       return LHS.Size < RHS.Size;
   }
-}
+} // namespace
 
 /// all_declared_ivar_begin - return first ivar declared in this class,
 /// its extensions and its implementation. Lazily build the list on first