examples/rust/profile: Use edition 2021

Switch the profile example over to using Rust edition 2021 for the
latest and greatest.

Signed-off-by: Daniel Müller <deso@posteo.net>

Author: d-e-s-o

examples/rust/profile/Cargo.toml

@@ -3,6 +3,7 @@ name = "profile"
 version = "0.1.0"
 authors = ["Kuifeng Lee <kuifeng@fb.com>"]
 license = "GPL-2.0 OR BSD-3-Clause"
+edition = "2021"
 
 [dependencies]
 libbpf-rs = "0.19"

examples/rust/profile/src/main.rs

@@ -6,25 +6,18 @@ use std::mem;
 use std::result::Result;
 use std::time::Duration;
 
-extern crate nix;
-use nix::unistd::close;
-
-extern crate libbpf_rs;
+use blazesym::symbolize;
 
-extern crate clap;
 use clap::Parser;
 
+use nix::unistd::close;
+
 #[path = "bpf/.output/profile.skel.rs"]
 mod profile;
-use profile::*;
-
-extern crate blazesym;
-use blazesym::symbolize;
-
-extern crate libc;
-
 mod syscall;
 
+use profile::*;
+
 const MAX_STACK_DEPTH: usize = 128;
 const TASK_COMM_LEN: usize = 16;