[$] Removing binder.c

The final talk at Kangrejos 2026 was about the removal of the C implementation of Android's Binder driver, the primary interprocess communication mechanism used on Android devices. Carlos Llamas announced that he had deleted the C code to general applause, and then shared some insights about what went into replacing the C implementation. Alice Ryhl, who has worked on the Rust implementation for some years, added her own thoughts about what the most difficult and interesting parts of the transition were.