Implement HMAC based on GOST 34.11-2012 Streebog-512 as well as a test
case for it. Both the PyGOST + hmac python module and the VeraCrypt HMAC
for Streebog-512 were used as references. The kernels expect the digests
to be in big-endian order according to the RFC examples for Streebog.
Fix two bugs from commit 224315dd62.
- Add hash-mode 11850: HMAC-Streebog-512 (key = $pass), big-endian
- Add test case for hash-mode 11850
- Bugfix for a3-pure Streebog kernels (modes 11700 and 11800)
- Rename a few Streebog constants in interface.h
a8eb611b1c