+ archive: don't convert syscall.Timespec to unix.Timespec
archive/tar_unix.go:179:76: error: invalid type conversion (cannot use type syscall.Timespec as type unix.Timespec)
179 | timespec := []unix.Timespec{unix.Timespec(fs.StatAtime(st)), unix.Timespec(fs.StatMtime(st))}
+ gccgo has no plugin support
https://github.com/golang/go/issues/36403
+ update github.com/containerd/continuity
to include same fix for Timespec
Signed-off-by: Shengjing Zhu <zhsj@debian.org>