Check name of test suite.
Check name of test suite.

If botan-test is invoked with an invalid test name, fail with a
usage error.  This is more obvious than not running the test.

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