all: upgrade x/sys to latest

This fixes a build error observed in
https://build.golang.org/log/13b332a441d4d18d5358f87f945cafba3d7b9d4e.

Change-Id: I7ea6ba6e6bbeb30dabc28952306b28997410d07a
Reviewed-on: https://go-review.googlesource.com/c/term/+/328150
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/go.mod b/go.mod
index bcbe5b5..edf0e5b 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@
 
 go 1.17
 
-require golang.org/x/sys v0.0.0-20201119102817-f84b799fce68
+require golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1
diff --git a/go.sum b/go.sum
index de9e09c..ff13213 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,2 @@
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 h1:nxC68pudNYkKU6jWhgrqdreuFiOQWj1Fs7T3VrH4Pjw=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 h1:SrN+KX8Art/Sf4HNj6Zcz06G7VEz+7w9tdXTPOZ7+l4=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=