Move an EMIT_MIR comment.

This belongs on a function, not a `use` declaration.

Author: nnethercote

tests/mir-opt/issue_76432.rs

@@ -3,9 +3,9 @@
 //@ compile-flags: -Zmir-enable-passes=-NormalizeArrayLen
 // Check that we do not insert StorageDead at each target if StorageDead was never seen
 
-// EMIT_MIR issue_76432.test.SimplifyComparisonIntegral.diff
 use std::fmt::Debug;
 
+// EMIT_MIR issue_76432.test.SimplifyComparisonIntegral.diff
 fn test<T: Copy + Debug + PartialEq>(x: T) {
     let v: &[T] = &[x, x, x];
     match v {