We now use INT64_MAX and INT64_MIN as the max and min values for
dimension_slice ranges. If a dimension_slice has a range_start of
INT64_MIN or the range_end is INT64_MAX, we remove the corresponding
check constraint on the chunk since it signifies that this end of the
range is infinite. Closed ranges now always have INT64_MIN as range_end
of first slice and range_end of INT64_MAX for the last slice.
Also, points corresponding to INT64_MAX are always
put in the same slice as INT64_MAX-1 to avoid problems with the
semantics that coordinate < range_end.