erofs-utils: add --hard-dereference option

erofs-utils: add --hard-dereference option

Add option --hard-dereference to dereference hardlinks when
creating an image. Instead of reusing the inode, hardlinks are added
as separate inodes. This is useful for reproducible builds, when the
rootfs is space-optimized using hardlinks on some machines, but not on
others.

Co-authored-by: Leonard Cohnen <leonard.cohnen@gmail.com>
Signed-off-by: Paul Meyer <katexochen0@gmail.com>
Link: https://lore.kernel.org/r/20241212165550.58756-1-katexochen0@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>