Copy ignoringEINTR2 from internal/poll and make use of it to remove
open-coded implementations.
Change-Id: I8802862f2012980f2af445b75eb45bb5a97bcc2a
Reviewed-on: https://go-review.googlesource.com/c/go/+/627479
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>