Rollup merge of #22583 - vhbit:ios-cstr, r=alexcrichton

   "body": null,

src/libstd/os.rs

@@ -595,7 +595,7 @@ fn real_args_as_bytes() -> Vec<Vec<u8>> {
 // res
 #[cfg(target_os = "ios")]
 fn real_args_as_bytes() -> Vec<Vec<u8>> {
-    use ffi::c_str_to_bytes;
+    use ffi::CStr;
     use iter::range;
     use mem;
 
@@ -630,7 +630,7 @@ fn real_args_as_bytes() -> Vec<Vec<u8>> {
             let tmp = objc_msgSend(args, objectAtSel, i);
             let utf_c_str: *const libc::c_char =
                 mem::transmute(objc_msgSend(tmp, utf8Sel));
-            res.push(c_str_to_bytes(&utf_c_str).to_vec());
+            res.push(CStr::from_ptr(utf_c_str).to_bytes().to_vec());
         }
     }