redox: Add semaphore functions

[willnode]

Description

This adds more semaphore.h functions to Redox. These functions existed since years ago and tested months ago for Golang thread synchronization. Now these are added to fix compilation related to new ctrlc crate.

Added in redox.rs

• sem_clockwait
• sem_destroy
• sem_getvalue
• sem_init
• sem_timedwait

Already in unix.rs

• sem_post
• sem_trywait
• sem_wait

Sources

• Relibc Source
• libc crate backport to fix ctrlc crate

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

@rustbot label +stable-nominated

[JohnTitor]

Thank you!

View changes since this review