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

https://github.com/tornaria/void-packages libmtp
https://github.com/void-linux/void-packages/pull/43589

libmtp: update to 1.1.21.
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#### Testing the changes
- I tested the changes in this PR: **briefly**

I have it installed, works ok with my garmin watch via `gmtp`.

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A patch file from https://github.com/void-linux/void-packages/pull/43589.patch is attached