message: [Formatter] Fix yesterday's incorrect merge
  Shafik changed `stl_synth_flags` -> `stl_deref_flags` but the merge
  conflict showed a totally different regex because it got changed
  upstream after the stable branch got cut.
diff: @@ -486,7 +486,7 @@ static void LoadLibCxxFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
  cpp_category_sp,
  lldb_private::formatters::LibcxxStdListSyntheticFrontEndCreator,
  "libc++ std::list synthetic children",
  - ConstString("^std::__(ndk)?1::list<.+>(( )?&)?$"), stl_deref_flags,
  + ConstString("^std::__[[:alnum:]]+::list<.+>(( )?&)?$"), stl_deref_flags,
  true);
  AddCXXSynthetic(
  cpp_category_sp,
  