tests: Add PBKDF2 tests for Stribog512.
* tests/t-kdf.c (check_pbkdf2): Add Stribog512 test cases from TC26's additions to PKCS#5.
Backport from master commit: a0580d446fef648a177ca4ab060d0e449780db84
- Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>