iotests: disable core dumps in test 061

iotests: disable core dumps in test 061

Commit 934659c460 disabled the supression of segmentation faults in
bash tests. The new output of test 061, however, assumes that a core
dump will be produced if a program aborts. This is not necessarily the
case because core dumps can be disabled using ulimit.

Since we cannot guarantee that abort() will produce a core dump, we
should use SIGKILL instead (that does not produce any) and update the
test output accordingly.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>