rust: use std::ffi instead of std::os::raw

This is allowed since Rust 1.64.0.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/qemu-api/tests/vmstate_tests.rs

@@ -2,7 +2,12 @@
 // Author(s): Zhao Liu <zhai1.liu@intel.com>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-use std::{ffi::CStr, mem::size_of, os::raw::c_void, ptr::NonNull, slice};
+use std::{
+    ffi::{c_void, CStr},
+    mem::size_of,
+    ptr::NonNull,
+    slice,
+};
 
 use qemu_api::{
     bindings::{