[PATCH v2] erofs-utils: lib: fix xattr crash in rebuild path when source has xattr

[Lucas Karpinski]

> Hi Lucus,
> 
> Can you confirm it that fixes your issue too?
> I will merge this for the bandaid solution, but after erofs-utils 1.9.1
> is released, rebuild and xattr codebase need to be fixed instead.
> 
> Thanks,
> Gao Xiang
Yes, confirmed that it does fix my issue as well.

Regards,
Lucas