e2fsck: report ext2fs_open2() and ext2fs_check_desc() errors

Print the actual errors returned by ext2fs_open2() and
ext2fs_check_desc() before we fall back to the backup block group
descriptors so that it's easier to see if there is some obscure
failure that is causing e2fsck to think that it should use the backup
block group descriptors.

Addresses-Google-Bug: #6208183

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
15 files changed