Updating protos version

Change-Id: I2889e2853e1660b816e4515656cdf01f49b2900a
diff --git a/vendor/golang.org/x/sys/unix/ztypes_darwin_amd64.go b/vendor/golang.org/x/sys/unix/ztypes_darwin_amd64.go
index 966798a..e6576d1 100644
--- a/vendor/golang.org/x/sys/unix/ztypes_darwin_amd64.go
+++ b/vendor/golang.org/x/sys/unix/ztypes_darwin_amd64.go
@@ -151,6 +151,10 @@
 	_       [3]byte
 }
 
+const (
+	PathMax = 0x400
+)
+
 type RawSockaddrInet4 struct {
 	Len    uint8
 	Family uint8