pin golang.org/x/sys due to breaking API change

vendor/golang.org/x/sys/unix/syscall_dragonfly.go

@@ -12,25 +12,7 @@
 
 package unix
 
-import (
-	"sync"
-	"unsafe"
-)
-
-// See version list in https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/param.h
-var (
-	osreldateOnce sync.Once
-	osreldate     uint32
-)
-
-// First __DragonFly_version after September 2019 ABI changes
-// http://lists.dragonflybsd.org/pipermail/users/2019-September/358280.html
-const _dragonflyABIChangeVersion = 500705
-
-func supportsABI(ver uint32) bool {
-	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
-	return osreldate >= ver
-}
+import "unsafe"
 
 // SockaddrDatalink implements the Sockaddr interface for AF_LINK type sockets.
 type SockaddrDatalink struct {
@@ -168,8 +150,6 @@ func setattrlistTimes(path string, times []Timespec, flags int) error {
 
 //sys	ioctl(fd int, req uint, arg uintptr) (err error)
 
-//sys   sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) = SYS___SYSCTL
-
 func sysctlUname(mib []_C_int, old *byte, oldlen *uintptr) error {
 	err := sysctl(mib, old, oldlen, nil, 0)
 	if err != nil {
@@ -308,7 +288,7 @@ func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 //sys	Revoke(path string) (err error)
 //sys	Rmdir(path string) (err error)
 //sys	Seek(fd int, offset int64, whence int) (newoffset int64, err error) = SYS_LSEEK
-//sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)
+//sys	Select(n int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (err error)
 //sysnb	Setegid(egid int) (err error)
 //sysnb	Seteuid(euid int) (err error)
 //sysnb	Setgid(gid int) (err error)