Fix seeding of test RNG
Fix seeding of test RNG

If no explicit seed was provided, it ended up ignoring the timestamp
derived seed.

randombit/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,randombit/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,webmaster128/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan