While this doesn't yet use any OS provided times from the actual network
stack, this still gets rid of any IPC jitter between the helper process
and the main process as part of the PTP time calculations and should
improve accuracy.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4665>
This works on Linux, Android, Windows, macOS, FreeBSD, NetBSD, OpenBSD,
DragonFlyBSD, Solaris and Illumos.
Newly supported compared to the C version is Windows.
Compared to the C version various error paths are handled more correctly
and a couple of memory leaks are fixed. Otherwise it should work identically.
The minimum required Rust version for compiling this is 1.48, i.e. the
version currently in Debian stable. On Windows, Rust 1.54 is needed at
least.
Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1259
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3889>
