Rollup merge of rust-lang#81095 - LingMan:unwrap, r=oli-obk

Use Option::unwrap_or instead of open-coding it

r? ```@oli-obk``` Noticed this while we were talking about the other PR just now 😆
```@rustbot``` modify labels +C-cleanup +T-compiler

Author: m-ou-se

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -214,11 +214,7 @@ fn handle_native(name: &str) -> &str {
 }
 
 pub fn target_cpu(sess: &Session) -> &str {
-    let name = match sess.opts.cg.target_cpu {
-        Some(ref s) => &**s,
-        None => &*sess.target.cpu,
-    };
-
+    let name = sess.opts.cg.target_cpu.as_ref().unwrap_or(&sess.target.cpu);
     handle_native(name)
 }