更新.gitignore, 避免显示乱七八糟的文件.

Signed-off-by: Jack <jack.wgm@gmail.com>
同步avhttp至最新版本.

Signed-off-by: Jack <jack.wgm@gmail.com>
更新libupdate实现, 修复使用last_modify选项.

Signed-off-by: Jack <jack.wgm@gmail.com>