There is an updated pull request by tornaria against master on the void-packages repository

https://github.com/tornaria/void-packages iperf
https://github.com/void-linux/void-packages/pull/42778

iperf: update to 2.1.9.
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#### Testing the changes
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A patch file from https://github.com/void-linux/void-packages/pull/42778.patch is attached