Let `noop()` use `std::os::raw::c_void` instead of `libc::c_void`
Let `noop()` use `std::os::raw::c_void` instead of `libc::c_void`

See discussions about libc:
    * https://github.com/rust-lang/rust/issues/31536
    * https://github.com/rust-lang/libc/issues/180
    * https://github.com/rust-lang/libc/issues/547

adamcrume/tensorflow-rust,tensorflow/rust,tensorflow/rust,tensorflow/rust,adamcrume/tensorflow-rust,adamcrume/tensorflow-rust,tensorflow/rust,adamcrume/tensorflow-rust