Add 78651

Locally running `cargo run` and running `rustc` directly produced different
results.

Call rustc on 78651 directly instead of indirectly (through cargo).

Issue: rust-lang/rust#78651

ices/78651.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+rustc - <<EOF
+use std::result;
+impl result {
+    fn into_future() -> Err {}
+}
+EOF