There's a merged pull request on the void-packages repository

bzip2-devel: add pkgconfig file
https://github.com/void-linux/void-packages/pull/40468

Description:
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Adapted from [Arch Linux](https://github.com/archlinux/svntogit-packages/commit/e2cc08098f31fc7110131782626d22939731b7d5)

Context: upstream has been unresponsive about requests for pkgconfig files in the past, but Arch and Alpine include their own, at least.
Also, the experimental future development project added the file back in 2019: https://gitlab.com/bzip2/bzip2/-/commit/70ec984159c8263fdd4aac7c4670977aff0fe5b3

#### Testing the changes
- I tested the changes in this PR: **briefly**

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