stat1.Mtim undefined in ztypes_darwin_amd64

[Melody12ab]

type Stat_t in the method populate of playlist.go has different modify time name with different kernel. ex: https://github.com/golang/go/blob/master/src/syscall/ztypes_linux_amd64.go#L114 https://github.com/golang/go/blob/master/src/syscall/ztypes_darwin_arm64.go#L75