Add symlinkat test case

Tests successful creation (using readlink() to verify the contents),
EEXIST, ENOENT cases.

Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Link: https://lore.kernel.org/r/20210603052906.2616489-6-dkadashev@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
3 files changed