internal/core/adt: change slice type of notify
This is to accomodate the new closedness algorithm.
Doing this now makes upcoming diffs smaller.
Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I786318a39635dfeb7dd1dd1fc854521e474ffe03
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1167912
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>