generic/258: check filesystem support for negative timestamps

generic/258: check filesystem support for negative timestamps

Some filesystems do not support negative c/m/atime timestamps. And
for these filesystems, generic/258 will fail.

Since there's currently no way to check sb->s_time_min from
userspace, this patch adds a new common/rc function
_require_negative_timestamps() that will _notrun depending on the
$FSTYP variable.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>