[release-branch.go1.16] go1.16

Change-Id: I4c1350e0cb74ebfde5832973979e02997476d16c
Reviewed-on: https://go-review.googlesource.com/c/go/+/292609
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Alexander Rakoczy <alex@golang.org>
Run-TryBot: Alexander Rakoczy <alex@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>

VERSION

@@ -1 +1 @@
-go1.16rc1
+go1.16