widen special case on deref to all non-zst allocators

src/test/ui/box/issue-95036.rs

@@ -0,0 +1,10 @@
+// compile-flags: -O
+// compile-pass
+
+#![feature(allocator_api, bench_black_box)]
+
+pub fn main() {
+    let mut node = Box::new_in([5u8], &std::alloc::Global);
+    node[0] = 7u8;
+    std::hint::black_box(node);
+}