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/DebugInfo/DWARF/SyntaxHighlighting.h b/llvm/lib/DebugInfo/DWARF/SyntaxHighlighting.h
index 946a313..84afd37 100644
--- a/llvm/lib/DebugInfo/DWARF/SyntaxHighlighting.h
+++ b/llvm/lib/DebugInfo/DWARF/SyntaxHighlighting.h
@@ -32,8 +32,8 @@
   llvm::raw_ostream& get() { return OS; }
   operator llvm::raw_ostream& () { return OS; }
 };
-}
-}
-}
+} // namespace syntax
+} // namespace dwarf
+} // namespace llvm
 
 #endif