Remove the shim kernel crate

kernel/src/syscall/shutdown.rs

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::SyscallReturn;
+use crate::{
+    fs::file_table::FileDesc, net::socket::SockShutdownCmd, prelude::*,
+    util::net::get_socket_from_fd,
+};
+
+pub fn sys_shutdown(sockfd: FileDesc, how: i32, _ctx: &Context) -> Result<SyscallReturn> {
+    let shutdown_cmd = SockShutdownCmd::try_from(how)?;
+    debug!("sockfd = {sockfd}, cmd = {shutdown_cmd:?}");
+
+    let socket = get_socket_from_fd(sockfd)?;
+    socket.shutdown(shutdown_cmd)?;
+    Ok(SyscallReturn::Return(0))
+}