#4940 Fix for build on Mac

[sosnovsky]

This PR fixes extension building in macOS

close #4940

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Tests (delete all except exactly one):

• Does not need tests (refactor only, docs or internal changes)

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To be filled by reviewers

I have reviewed that this PR... (tick whichever items you personally focused on during this review):

• addresses the issue it closes (if any)
• code is readable and understandable
• is accompanied with tests, or tests are not needed
• is free of vulnerabilities
• is documented clearly and usefully, or doesn't need documentation

[rrrooommmaaa]

Hi @sosnovsky
I'm having the bak files piling up after each build. Perhaps, it'd be better to delete them?

[sosnovsky]

@rrrooommmaaa I updated build script to not produce .bak files in new PR - #4945
macOS and Linux have a bit different syntaxes for sed command, so I just added conditional check for the current OS