Tracking issues for removing the `newlib` feature

We should get C application support on par with the Rust application support and remove most special cases for C.

- [ ] https://github.com/hermit-os/kernel/pull/656
- [x] https://github.com/hermit-os/kernel/pull/1165
- [ ] https://github.com/hermit-os/kernel/pull/1166
- [x] https://github.com/hermit-os/kernel/pull/1169
- [ ] Remove semaphore