all: update dependency on golang.org/x/sys and regenerate Windows syscalls

Steps run:

	$ cd $(go env GOROOT)/src
	$ go get -d golang.org/x/sys
	$ go mod tidy
	$ go mod vendor
	$ go generate syscall/... internal/syscall/...
	$ cd cmd
	$ go get -d golang.org/x/sys
	$ go mod tidy
	$ go mod vendor
	$ cd ..
	$ git add .

This change subsumes CL 260860.

For #36905

Change-Id: I7c677c6aa1ad61b9cbd8cf9ed208ed5a30f29c87
Reviewed-on: https://go-review.googlesource.com/c/go/+/267103


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>