Use of these functions is almost (but not) always a bad idea.
Very rarely they are necessary, and third-party implementations
(using a mutex and an atomic word, say) cannot integrate as well
with the race detector as implmentations in package sync itself.
Fixes #45435.
Change-Id: I0128ca48ef5e0a3b09c913f0f3a7ee5c56388000
Reviewed-on: https://go-review.googlesource.com/c/go/+/319769
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>