gh-38025: `fflas_ffpack`, `linbox`: Switch to release tarballs with working libtool
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These fix the build on macOS, as discussed in #38020.
Test run:
https://github.com/mkoeppe/sage/actions/runs/9142716213/job/25138580652
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### :hourglass: Dependencies
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- Depends on #38020 (merged and partially reverted here)
- Depends on #37726 (merged here to resolve merge conflict)
URL: https://github.com/sagemath/sage/pull/38025
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee, Matthias Köppe
