Auto merge of #1877 - hyd-dev:rustup, r=RalfJung

Add `#[allow(unreachable_code)]` to `drop(x)` in `tests/run-pass/generator.rs`

The test [starts to trigger this warning](https://github.com/rust-lang/miri/runs/3408355084?check_suite_focus=true#step:8:264) (I guess it's caused by rust-lang/rust#85556). The warning seems correct, but the unreachable code in that test also seems reasonable.

rust-version

@@ -1 +1 @@
-73d96b090bb68065cd3a469b27cbd568e39bf0e7
+f66e825f73d2bd7f8a763b723983850f891985b0

tests/run-pass/generator.rs

@@ -94,6 +94,7 @@ fn never() -> Never {
         #[allow(unused)]
         let x = never();
         yield 2;
+        #[allow(unreachable_code)]
         drop(x);
     });