fstests: transport two ext4 tests from LTP
Recently LTP upstream removed some ext4 tests[1]. And two of them
is still valid to keep. So I transport those two tests here.
ext4-nsec-timestamps, which is used to test nanosec timestamps of
ext4, rewrite into ext4/043 and 044. ext4-subdir-limit, which is
used to test subdirectory limit of ext4, rewrite into ext4/045.
[1] https://marc.info/?l=linux-fsdevel&m=
157190623919681&w=2
Signed-off-by: Sun Yong <yosun@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>