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

stepmania: fix build with gcc 12, ship ffmpeg 2.1.3 with distfiles
https://github.com/void-linux/void-packages/pull/40783

Description:
If ffmpeg with specific version is not present in the work source directory, cmake attempts to clone its repository with git and check out version 2.1.3. This approach presents two issues:

1. It can no longer be cloned using git:// for github (see https://github.com/stepmania/stepmania/pull/2200) which results in connection timeout and build failure as the result.

2. Downloaded tarball is erased after successful build since it is considered to be part of the source code.
Its retrieval and storage for future use should be done by xbps-src.

cc: @the-maldridge as the current maintainer of the package.

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

#### Local build testing
- I built this PR locally for my native architecture, x86_64