ext4: regression test for "tune2fs -l" after ext4 shutdown

ext4: regression test for "tune2fs -l" after ext4 shutdown

Regression test for e2fsprogs commit:

e905fbe3fd0f ext4: Fix tune2fs checksum failure for mounted filesystem

This test runs "tune2fs -l" after ext4 shutdown. tune2fs reads
superblock checksum from the buffer cache. On unfixed kernels, the
checksum is incorrect until the writeout happens, so tune2fs fails
with "superblock checksum does not match" in this case.

Signed-off-by: Boyang Xue <bxue@redhat.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>