cmd/go/internal/renameio: include ios in the darwin test-flake mitigation
Because the "ios" build constraint implies "darwin", it is already
included in the general "darwin" flakiness workaround in
cmd/go/internal/robustio. We just need to relax the renameio test
to avoid false-positives there.
I do not expect this change to drive the rate of false-positives down
to zero, but it should at least reduce noise on the build dashboard.
For #42066
Change-Id: Ia33dbd33295fce5b3261b4831f2807ce29b82e65
Reviewed-on: https://go-review.googlesource.com/c/go/+/263777
Trust: Bryan C. Mills <bcmills@google.com> Reviewed-by: Cherry Zhang <cherryyz@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>