internal/core/adt: make small iota enums consistently uint8
The vast majority of them were already uint8 (or int8), but two were
int for no apparent reason. This takes up more space for no benefit.
│ old │ new │
│ sec/op │ sec/op vs base │
VetAutomata 932.0m ± 13% 920.9m ± 14% ~ (p=0.485 n=6)
│ old │ new │
│ B/op │ B/op vs base │
VetAutomata 701.9Mi ± 0% 700.7Mi ± 0% -0.17% (p=0.002 n=6)
│ old │ new │
│ allocs/op │ allocs/op vs base │
VetAutomata 4.478M ± 0% 4.478M ± 0% ~ (p=0.699 n=6)
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I14c994e3e29505c569d56f5ed01e56beabb864c1
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1217117
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>