Judging from https://github.com/libffi/libffi, they could do with more contributors/support over there.

I see a bunch of reports along these lines from a few years back, apparently someone has a test suite that covers it, but hasn't merged it into the libffi test suite which is where it really belongs.

If it turns out to be a straightforward fix, we're able to patch our own build rather than waiting for a libffi release (and since we're unlikely to get new 3.3 releases for 3.10 and earlier, that's what we'll need to release it in updates). But we don't run their test suite on our build, so we'd want it to be upstream as well.