[0.2] Revert "musl: convert inline timespecs to timespec"

[heiher]

Description

This reverts commit 55fa65b, as suggested by #4942 (comment).

Fixes #4939

Sources

• https://github.com/kraj/musl/tree/v1.1.20
• https://github.com/kraj/musl/tree/v1.2.5

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]

⚠️ Warning ⚠️

• Pull requests are usually filed against the main branch for this repo, but this one is against libc-0.2. Please double check that you specified the right target!