signalapp/webrtc ? reverse-engineered prompt

Build me a working version of this custom WebRTC fork for use with RingRTC.

I want the native code compiling cleanly and the Rust FFI hooks wired in, plus Android and iOS SDK outputs that keep the extra control and customization this fork is supposed to have. Please preserve the fork specific behavior, including ICE forking, the reduced RTP header extensions and audio codecs, and any security fixes that are already part of it.

If there are example targets or basic test builds, get those running too so I can tell the fork is actually usable. When you’re done, leave me with simple build and run steps, and a short plain English note on how this differs from normal WebRTC. You can look up current WebRTC native build docs online if you need to.