Merge pull request #3 from thaJeztah/wrap_no_alias

use wrapper function instead of variable for freebsd

Author: thaJeztah

dev_freebsd.go

@@ -4,4 +4,6 @@ package archive
 
 import "golang.org/x/sys/unix"
 
-var mknod = unix.Mknod
+func mknod(path string, mode uint32, dev uint64) error {
+	return unix.Mknod(path, mode, dev)
+}