Add additional debug information for libcurl on m1 mac in readme

[sirknightj]

When building latest master on my m1 mac, I needed to run brew unlink openssl for it to build correctly.

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[stefankiesz]

Mac GCC and Windows MSVC CI build errors were fixed in this merge. You can rebase to include those changes.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (22f365e) 16.34% compared to head (9f035c8) 16.33%.

❗ Current head 9f035c8 differs from pull request most recent head f70e514. Consider uploading reports for the commit f70e514 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1107      +/-   ##
===========================================
- Coverage    16.34%   16.33%   -0.02%     
===========================================
  Files           51       51              
  Lines         6846     6846              
===========================================
- Hits          1119     1118       -1     
- Misses        5727     5728       +1     

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