Re: [Spark 2.x Core] .collect() size limit

[Vadim Semenov]

`.collect` returns an Array, and array's can't have more than Int.MaxValue
elements, and in most JVMs it's lower: `Int.MaxValue - 8`
So it puts upper limit, however, you can just create Array of Arrays, and
so on, basically limitless, albeit with some gymnastics.