[dev.simd] go/doc/comment: don't include experimental packages in std list
go/doc/comment/std.go has a list of top-level package prefixes in
the standard library. This list can vary depending on goexperiment,
but the file is static. E.g.
GOEXPERIMENT=arenas go test -run=TestStd go/doc/comment
would fail.
Don't include experimental packages, as they are not (yet)
generally available. We could have a per-experiment list of
package prefixes. But given that experimental packages are not
intended to be used widely (yet), it is probably not worth the
complexity.
Change-Id: Ib5bc060297cbae29c01fee458aaaa29600b81e98
Reviewed-on: https://go-review.googlesource.com/c/go/+/723840
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com>