Fixes two ways an incoming message could go missing silently.

- The Android SMS store reuses the row id of a deleted message. Clear SMS
  treated that id as permanent, so after you deleted or blocked something,
  the next message arriving with a reused id was mistaken for one already
  seen and dropped - it stayed in the system store but never appeared in
  the app. Blocking a sender made this very likely.
- A message arriving at the same moment you changed a setting (block a
  sender, add a keyword, toggle the recycle bin) could get stuck waiting
  on that setting and never be stored.
