db_test: also test db_get_auc() return values

Verify that it returns -ENOENT on non-existing IMSI and -ENOKEY for no auth
data.

Move the auc_compute_vectors() stub to the top near the db_get_auc() call, and
just return num_vec to get a successful return value when auth data is present.

Change-Id: Ic0158228afbd78b8ca21f62dffa9f868674682b9
2 files changed