A few more hlint fixes

I'm ignoring the use of Control.Arrow.*** since it's a non-obvious
function, and we're not widely using Arrows in the code base, so I
think switching to it would make the code less readable to most
people.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>