message: docs: Update changelog
  Mention ubsan fixes; these fixes probably fix compact mode on some
  64-bit architecture where unaligned pointer reads aren't valid as well
  but it's probably not very relevant...
diff: @@ -2144,6 +2144,7 @@ Because of the differences in document object models, performance considerations
  . Fix implicit fallthrough warnings in gcc 7
  . Fix cray++ compiler errors
  . Fix unsigned integer overflow errors with -fsanitize=integer
  + . Fix undefined behavior sanitizer issues in compact mode
  [[v1.8]]
  === v1.8 ^2016-11-24^
  