Could switch to bbolt from bolt?

[bo]

hi,

I am trying to fix the ftbfs issue on Debian riscv64.
https://buildd.debian.org/status/logs.php?pkg=snapd&arch=riscv64

The issue was due to lack of riscv64 support on bolt from its build log:

```

# github.com/boltdb/bolt
src/github.com/boltdb/bolt/db.go:101:13: undefined array length maxMapSize or missing type constraint
src/github.com/boltdb/bolt/db.go:317:12: undefined: maxMapSize
src/github.com/boltdb/bolt/db.go:335:10: undefined: maxMapSize
src/github.com/boltdb/bolt/db.go:336:8: undefined: maxMapSize
src/github.com/boltdb/bolt/bolt_unix.go:62:15: undefined array length maxMapSize or missing type constraint
src/github.com/boltdb/bolt/bucket.go:135:15: undefined: brokenUnaligned
src/github.com/boltdb/bolt/freelist.go:166:2: idx declared and not used
src/github.com/boltdb/bolt/freelist.go:169:19: undefined array length maxAllocSize or missing type constraint
src/github.com/boltdb/bolt/freelist.go:176:14: undefined array length maxAllocSize or missing type constraint
src/github.com/boltdb/bolt/freelist.go:204:17: undefined array length maxAllocSize or missing type constraint
src/github.com/boltdb/bolt/freelist.go:204:17: too many errors
```

See the buildd log:
https://buildd.debian.org/status/fetch.php?pkg=snapd&arch=riscv64&ver=2.61.1-1&stamp=1706526162&raw=0

But from snapd upstream side, we have supported riscv64 for a long time:
https://github.com/snapcore/snapd/pull/8801

But unfortunately, the Debian snapd maintainer uses boltdb/bolt instead of vendor bolt which supports riscv64. The boltdb/bolt has been archived for a long time.

To fix the issue, we have below solutions:
1. On Debian to package snapcore/bolt, but it's hard to let Debian accept one vendor go modules which for some years does not update.
2. To backport riscv64 support on boltdb/bolt on Debian, but from my knowledge on debian-go team, they will reduce to support on golang-github-boltdb-bolt until remove it, see: https://tracker.debian.org/pkg/golang-github-boltdb-bolt (from here we know there is no value to package snapcore/bolt on Debian again)
3. We switch to bbolt(https://tracker.debian.org/pkg/golang-github-coreos-bbolt or https://github.com/etcd-io/bbolt) from bolt, this will become easy to maintain from every aspect. But I am not sure how many work need to be finished here.

More background to see:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1010686