net: move go/cgo resolver forcing functions to one file
The forceGoDNS/forceCgoDNS functions currently return nil
or an empty func on plan9, but they don't have to, because
we already support go resolver there (Dial field required).
Change-Id: Iba6211ca0235874f39e5fcacb3932bb16768c702
GitHub-Last-Rev:
4072ad4a05366a03749e8cfcf27efb9f198aacec
GitHub-Pull-Request: golang/go#63545
Reviewed-on: https://go-review.googlesource.com/c/go/+/534938
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Commit-Queue: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>