[$] Removing binder.c

The final talk at Kangrejos 2026 was about the removal of the C implementationof Android'sBinder driver, the primary interprocess communication mechanismused on Android devices. Carlos Llamas announced that he had deleted the Ccode to general applause, and then shared some insights about what went intoreplacing the C implementation. Alice Ryhl, who has worked on the Rustimplementation for some years, added her own thoughts about what the mostdifficult and interesting parts of the transition were.