Shut up some rust warnings

nix-rust/src/error.rs

@@ -26,5 +26,6 @@ impl From<Error> for CppException {
 pub struct CppException(*const libc::c_void); // == std::exception_ptr*
 
 extern "C" {
+    #[allow(improper_ctypes)] // YOLO
     fn make_error(s: &str) -> CppException;
 }

nix-rust/src/lib.rs

@@ -5,7 +5,7 @@ mod tarfile;
 pub use error::Error;
 
 pub struct CBox<T> {
-    ptr: *mut libc::c_void,
+    pub ptr: *mut libc::c_void,
     phantom: std::marker::PhantomData<T>,
 }