Module libc/darwin

Darwin-only C interface pieces (audit env row: vars()).

macOS does not export environ through the regular headers; the sanctioned route is <crt_externs.h>'s _NSGetEnviron(). This module is only ever imported from a Platform.Macos comptime arm, so the header include never reaches other platforms' emitted C.

Stability

unstable — a raw C binding that exists to serve exactly one caller: std/env's vars() on macOS. The public surface is std/env, and this module follows Darwin rather than a Yo design — _NSGetEnviron is Apple's sanctioned replacement for the environ symbol std/libc/unistd binds on other Unixes. Anything else Darwin-only that std/ comes to need lands here, so the surface is additive-by-demand and not frozen.