Replace OSSpinLock with pthread_mutex

[chrisamanse]

New Pull Request Checklist

• I have read and understood the CONTRIBUTING guide

• I have read the Documentation

• I have searched for a similar pull request in the project and found none

• I have updated this branch with the latest master to avoid conflicts (via merge from master or rebase)

• I have added the required tests to prove the fix/feature I am adding

• I have updated the documentation (if necesarry)

• I have run the tests and they pass

• I have run the lint and it passes (pod lib lint)

This merge request fixes / refers to the following issues: ...

Pull Request Description

Replace OSSpinLock with pthread_mutex. Related issue: #886.

[codecov-io]

Codecov Report

Merging #889 into master will decrease coverage by 0.03%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #889      +/-   ##
==========================================
- Coverage   21.26%   21.23%   -0.04%     
==========================================
  Files          18       18              
  Lines        2633     2637       +4     
  Branches      282      282              
==========================================
  Hits          560      560              
- Misses       2033     2037       +4     
  Partials       40       40

Impacted Files	Coverage Δ
Classes/Extensions/DDContextFilterLogFormatter.m	0% <0%> (ø)	⬆️
Classes/Extensions/DDDispatchQueueLogFormatter.m	0% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d9bed4d...d3ba0f9. Read the comment docs.