Fix compilation with Rust 1.63. (#1017)

* Fix compilation with Rust 1.63.

Rust 1.63 doesn't have `core::ffi::c_int`, so use the `c_int` from libc
or linux-raw-sys.

* Update the install-rust action to node20.

Author: sunfishcode

.github/actions/install-rust/action.yml

@@ -8,5 +8,5 @@ inputs:
     default: 'stable'
 
 runs:
-  using: node16
+  using: node20
   main: 'main.js'

src/system.rs

@@ -7,7 +7,7 @@
 #![allow(unsafe_code)]
 
 use crate::backend;
-#[cfg(target_os = "linux")]
+#[cfg(any(linux_raw, target_os = "linux"))]
 use crate::backend::c;
 use crate::ffi::CStr;
 #[cfg(not(any(target_os = "espidf", target_os = "emscripten", target_os = "vita")))]
@@ -20,7 +20,7 @@ pub use backend::system::types::Sysinfo;
 #[cfg(linux_raw)]
 use crate::fd::AsFd;
 #[cfg(linux_raw)]
-use core::ffi::c_int;
+use c::c_int;
 
 /// `uname()`—Returns high-level information about the runtime OS and
 /// hardware.