bcmatroska2-0.23~git.20210209-bp154.1.55

- Update to latest commit in order to be able to build the
  latest version of mediastreamer2.
  The 'Provides' field was added because we need mediastreamer2 to
  depend on this latest version of the library, but upstream didn't
  release a new tag.
- Rebase bcmatroska2-include-subdir.patch

- %make_jobs is depricated replaced by %cmake_build

- Remove obsolete Groups tag (fate#326485)

- Modernise spec file

- Initial package.