Fix alignment again and add assert checks so we don't mess up again.
Fix alignment again and add assert checks so we don't mess up again.

We previously ignored a block that was exactly the right size for the
allocation and the needed alignment. If we find such a block prefer it
over any other (non-exact) blocks to minimize fragmentation.

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