Fix configuration on platforms without shared objects.
Fix configuration on platforms without shared objects.

Was calling on a None object and failing, noticed by MinGW cross build.

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