Adjust tests for new drop and forget lints

Author: Urgau

tests/fail/stacked_borrows/illegal_write2.rs

@@ -1,3 +1,5 @@
+#![allow(drop_ref)]
+
 fn main() {
     let target = &mut 42;
     let target2 = target as *mut _;

tests/fail/uninit_buffer.rs

@@ -1,5 +1,7 @@
 //@error-pattern: memory is uninitialized at [0x4..0x10]
 
+#![allow(drop_copy)]
+
 use std::alloc::{alloc, dealloc, Layout};
 use std::slice::from_raw_parts;
 

tests/fail/uninit_buffer_with_provenance.rs

@@ -2,6 +2,8 @@
 //@normalize-stderr-test: "a[0-9]+" -> "ALLOC"
 #![feature(strict_provenance)]
 
+#![allow(drop_copy)]
+
 // Test printing allocations that contain single-byte provenance.
 
 use std::alloc::{alloc, dealloc, Layout};

tests/pass/stacked-borrows/zst-field-retagging-terminates.rs

@@ -1,5 +1,8 @@
 //@compile-flags: -Zmiri-retag-fields
 // Checks that the test does not run forever (which relies on a fast path).
+
+#![allow(drop_copy)]
+
 fn main() {
     let array = [(); usize::MAX];
     drop(array); // Pass the array to a function, retagging its fields