tests/t-mpi-point: Add one more NIST P-256 reduction test-vector.
* tests/t-mpi-point.c (check_ec_mul_reduction): Add second NIST P-256 test vector from T5510.
Cherry-pick master commit of:
3f4a59299134c6804c5d29fb3f275ea0e04ac8ac
- GnuPG-bug-id: T5510
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>