Re: GIN improvements part2: fast scan

In addition to that, I'm using the ternary consistent function to check
if minItem is a match, even if we haven't loaded all the entries yet.
That's less important, but I think for something like "rare1 | (rare2 &
frequent)" it might be useful. It would allow us to skip fetching
'frequent', when we already know that 'rare1' matches for the current
item. I'm not sure if that's worth the cycles, but it seemed like an
obvious thing to do, now that we have the ternary consistent function.

So, that clearly isn't worth the cycles :-). At least not with an expensive consistent function; it might be worthwhile if we pre-build the truth-table, or cache the results of the consistent function.