fix build on Plan 9

[fhs]

Fixes #7575
Fixes #7671

ipfs/go-ds-badger#100 should be merged before this PR. I'm using an indirect dependency as a workaround. (done)

[welcome]

Thank you for submitting this PR!
A maintainer will be here shortly to review it.
We are super grateful, but we are also overloaded! Help us by making sure that:

• The context for this PR is clear, with relevant discussion, decisions
  and stakeholders linked/mentioned.

• Your contribution itself is clear (code comments, self-review for the
  rest) and in its best form. Follow the code contribution
  guidelines
  if they apply.

Getting other community members to do a review would be great help too on complex PRs (you can ask in the chats/forums). If you are unsure about something, just leave us a comment.
Next steps:

• A maintainer will triage and assign priority to this PR, commenting on
  any missing things and potentially assigning a reviewer for high
  priority items.

• The PR gets reviews, discussed and approvals as needed.

• The PR is merged by maintainers when it has been approved and comments addressed.

We currently aim to provide initial feedback/triaging within two business days. Please keep an eye on any labelling actions, as these will indicate priorities and status of your contribution.
We are very grateful for your contribution!

[willscott]

the badger dep update merged to master, do you need a release of go-ds-badger for this to refer to?

[fhs]

the badger dep update merged to master, do you need a release of go-ds-badger for this to refer to?

@willscott Yes, I need a new release of go-ds-badger. Thanks.

[willscott]

https:/ipfs/go-ds-badger/releases/tag/v0.2.5

[fhs]

I've updated go-ds-badger to the new version. This PR is ready for review.

[willscott]

Looks good to me. @aschmahmann for second review / merge

[aschmahmann]

Looks good, thanks 😄. Just added a question about a dependency change.

Also, it looks like the sharness tests are failing (perhaps due to the dependency change).