fn add_to_ancillary_data<T>(
buffer: &mut [u8],
length: &mut usize,
source: &[T],
cmsg_level: c_int,
cmsg_type: c_int,
) -> boolAvailable on (Android or Cygwin or Linux) and non-Hermit and not ((Fortanix and SGX, or WebAssembly and non-WASI)) and (Unix) only.