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

firefox-esr: update to 91.4.0, add ppc64le JIT patch
https://github.com/void-linux/void-packages/pull/34712

Description:
This PR adds completed second-stage JIT functionality for Firefox on POWER9 little-endian, described [here](https://www.talospace.com/2021/12/91esr-with-baseline-compilerbaseline.html) ([patch source](https://github.com/chmeeedalf/gecko-dev/issues/2)). The JIT code itself is conditionally downloaded for ppc64le only, and other platforms should be completely unaffected. The baseline for Void on ppc64le is POWER8, which is not (yet) supported by this JIT, but Firefox will detect this at runtime and disable the JIT if not running on POWER9. (However, this appears to be untested.)

This is marked as a draft because I haven't built it yet; I should be able to try it out soon, but I wanted to get the PR out there so folks could test it if they're so inclined.

This PR supersedes #34447.

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