Apply multi-arch hints

Apply hints suggested by the multi-arch hinter.

• libblitz0-dev: Drop Multi-Arch: same. This fixes: libblitz0-dev conflicts on /usr/include/blitz/gnu/bzconfig.h on any two of amd64, arm64, armel, armhf, and 5 more. (file-conflict)

Note that in some cases, these multi-arch hints may trigger lintian warnings until the dependencies of the package support multi-arch. This is expected, see https://janitor.debian.net/multiarch-fixes#why-does-lintian-warn for details.

This merge proposal was created by the Janitor bot, and it will automatically rebase or close this proposal as appropriate when the target branch changes. Any comments you leave here will be read by the Janitor's maintainers.

Build and test logs for this branch can be found at https://janitor.debian.net/multiarch-fixes/pkg/blitz++/237ac5f8-9551-49ac-b9c5-f519dab05591.