vendor: update to the latest systemd_ctypes

We didn't sync this in a while and there have been a lot of changes.

We also have a critical bug fix included: we recently introduced a test
case (in 0bb7438) which triggers a
segfault in the binding layer of systemd_ctypes due to FFI call
trampolines being garbage collected while they're still running.

This is currently blocking downstream packaging on several non-x86_64
architectures.