alnyan/yggdrasil: implement exit()

library/std/src/sys/yggdrasil/os.rs

@@ -65,8 +65,9 @@ pub fn chdir(_path: &Path) -> io::Result<()> {
     todo!();
 }
 
-pub fn exit(_code: i32) -> ! {
-    todo!();
+pub fn exit(code: i32) -> ! {
+    use yggdrasil_rt::process::ExitCode;
+    unsafe { yggdrasil_rt::sys::exit_process(ExitCode::Exited(code)) }
 }
 
 pub fn getpid() -> u32 {