stream_open related bits for Linux 5.3

- the first one converts stream_open.cocci to treat all functions that
  start with wait_.* as blocking. Previously it was only wait_event_.*
  functions that were considered as blocking, but this was falsely
  reporting several deadlock cases as only warning. The patch was
  picked by linux-kbuild and entered mainline as 0c4ab18fc33b.
  It is thus omitted from hereby pull-request.

- the second one teaches stream_open.cocci to consider files as being
  stream-like even if they use noop_llseek. I posted this patch for
  review 3 weeks ago[1], but got neither feedback nor complaints.

  [1] https://lore.kernel.org/lkml/20190623072838.31234-2-kirr@nexedi.com/
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