Fix user name, group name and link count display (#829)

These type assertions for `Stat_t` were changed from `syscall` to
the incorrect `unix` ones in c5bd676.

Fixes #800.

os.go

@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+	"syscall"
 
 	"golang.org/x/sys/unix"
 )
@@ -177,7 +178,7 @@ func isHidden(f os.FileInfo, path string, hiddenfiles []string) bool {
 }
 
 func userName(f os.FileInfo) string {
-	if stat, ok := f.Sys().(*unix.Stat_t); ok {
+	if stat, ok := f.Sys().(*syscall.Stat_t); ok {
 		if u, err := user.LookupId(fmt.Sprint(stat.Uid)); err == nil {
 			return fmt.Sprintf("%v ", u.Username)
 		}
@@ -186,7 +187,7 @@ func userName(f os.FileInfo) string {
 }
 
 func groupName(f os.FileInfo) string {
-	if stat, ok := f.Sys().(*unix.Stat_t); ok {
+	if stat, ok := f.Sys().(*syscall.Stat_t); ok {
 		if g, err := user.LookupGroupId(fmt.Sprint(stat.Gid)); err == nil {
 			return fmt.Sprintf("%v ", g.Name)
 		}
@@ -195,7 +196,7 @@ func groupName(f os.FileInfo) string {
 }
 
 func linkCount(f os.FileInfo) string {
-	if stat, ok := f.Sys().(*unix.Stat_t); ok {
+	if stat, ok := f.Sys().(*syscall.Stat_t); ok {
 		return fmt.Sprintf("%v ", stat.Nlink)
 	}
 	return ""