sync.Map was introduced in Go 1.9, this change updates the syncmap package to use a type alias
to sync.Map for 1.9 and later. It also updates the comments to reflect this change.
Fixesgolang/go#33867
Change-Id: Ia58ad2bc409f8fcb8a7539ef165148315da5cfb1
Reviewed-on: https://go-review.googlesource.com/c/sync/+/192737
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
