erofs-utils: support calculating checksum of superblock

Added code for calculating crc of superblock.

Note that the first 1024 bytes are not checksummed to allow
for the installation of x86 boot sectors and other oddities.

Fill 'feature_compat' field of erofs_super_block so that it
can be used on kernel side. also fixing one typo.

Link: https://lore.kernel.org/r/20191107040327.93369-1-gaoxiang25@huawei.com
Signed-off-by: Pratik Shinde <pratikshinde320@gmail.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Reviewed-by: Li Guifu <blucerlee@gmail.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
5 files changed