[PATCH] erofs-utils: wrap up sb feature operations

[Li Guifu]

> Add some helpers for shorter lines. No logic change.
> 
> Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
> 

It looks good
Reviewed-by: Li Guifu <blucer.lee at foxmail.com>


Because the pre email Li Guifu <blucerlee at gmail.com> is not work at
chinese mainland, so replace it with Li Guifu <blucer.lee at foxmail.com>

Thanks,