问题已经解决, 通过寻找rust-openssl的issues, 得知:

openssl-sys v0.9.53 was released 3 years ago, and does not support your OpenSSL version. Run cargo update.

openssl-sys v0.9.53是3年前发布的，不支持OpenSSL版本。运行cargo update。 感觉报错情况差不多, 参考一下, 在目录下执行以下命令:

[root_cn@archlinux rustbuster]$ pwd
/home/root_cn/rust/rustbuster
[root_cn@archlinux rustbuster]$ cargo update
[root_cn@archlinux rustbuster]$ cargo build

运行成功,顺便找到一行未被使用的函数:

warning: function `configuration` is never used
  --> src/banner.rs:29:8
   |
29 | pub fn configuration(mode: &str, url: &str, threads: &str, wordlist: &str) -> String {
   |        ^^^^^^^^^^^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: `rustbuster` (bin "rustbuster") generated 1 warning
    Finished dev [unoptimized + debuginfo] target(s) in 2m 59s
warning: the following packages contain code that will be rejected by a future version of Rust: criterion v0.2.11
note: to see what the problems were, use the option `--future-incompat-report`, or run `cargo report future-incompatibilities --id 1`