Resolve "Render config reader MSVC fix from #705 causes issues on other platforms"

• Related issues: #1503
• Requested reviewers: @norvell, @szczerba

Reason why this change is needed

• See issue.

Description of the change

• Add #ifdef _MSC_VER around the call to setvbuf().

Affected operating points

• Render config file reading on non-Windows platforms