use sys/unix package instead of syscall (#1340)

According to the golang docs, the syscall package is deprecated.
https://golang.org/pkg/syscall
This updates collectors to use the x/sys/unix package instead.
Also updates the vendored x/sys/unix module to latest.

Signed-off-by: Paul Gier <pgier@redhat.com>

vendor/golang.org/x/sys/windows/mkerrors.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build generate
+
 package windows
 
 //go:generate ./mkerrors.bash zerrors_windows.go

vendor/golang.org/x/sys/windows/mksyscall.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build generate
+
 package windows
 
 //go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go eventlog.go service.go syscall_windows.go security_windows.go

vendor/golang.org/x/sys/windows/registry/mksyscall.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build generate
+
 package registry
 
 //go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall.go