pthread: implement cleanup_push/_pop

[lukileczo]

fixes phoenix-rtos/phoenix-rtos-project#827

DONE: RTOS-671

Description

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: libc/pthread: add tests for pthread_cleanup phoenix-rtos-tests#289
• Tested by hand on: (list targets here).

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work (list the PRs, preferably in merge-order).
• I will merge this PR by myself when appropriate.

[github-actions]

Unit Test Results

5 949 tests  ±0   5 296 ✔️ ±0   28m 59s ⏱️ -52s
   325 suites ±0      653 💤 ±0 
       1 files   ±0          0 ❌ ±0 

Results for commit 4f9a7b4. ± Comparison against base commit 44458bf.

♻️ This comment has been updated with latest results.

[agkaminski]

LGTM