gh-35284: primesieve/count update, add gentoo packages info for them
### 📚 primesieve/count update
primesieve and primecount update, add gentoo packages info for them
### 📝 Checklist
- [X] I have made sure that the title is self-explanatory and the
description concisely explains the PR.
- [ ] I have linked an issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation accordingly.
A straightforward upgrade
URL: https://github.com/sagemath/sage/pull/35284
Reported by: Dima Pasechnik
Reviewer(s): François Bissey
