ices/87496.rs: fixed with no errors

[github-actions]

Issue: rust-lang/rust#87496

#[repr(transparent)]
struct TransparentCustomZst(());
extern "C" {
    fn good17(p: TransparentCustomZst);
}

fn main() {}

=== stdout ===
=== stderr ===
warning: struct is never constructed: `TransparentCustomZst`
 --> /home/runner/work/glacier/glacier/ices/87496.rs:2:8
  |
2 | struct TransparentCustomZst(());
  |        ^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: function is never used: `good17`
 --> /home/runner/work/glacier/glacier/ices/87496.rs:4:5
  |
4 |     fn good17(p: TransparentCustomZst);
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: `extern` block uses type `TransparentCustomZst`, which is not FFI-safe
 --> /home/runner/work/glacier/glacier/ices/87496.rs:4:18
  |
4 |     fn good17(p: TransparentCustomZst);
  |                  ^^^^^^^^^^^^^^^^^^^^ not FFI-safe
  |
  = note: `#[warn(improper_ctypes)]` on by default
  = note: this struct contains only zero-sized fields
note: the type is defined here
 --> /home/runner/work/glacier/glacier/ices/87496.rs:2:1
  |
2 | struct TransparentCustomZst(());
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 3 warnings emitted

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