compiletests: update ptr_copy stderr for extra pointer-cast diagnostic

Author: LegNeato

tests/compiletests/ui/dis/ptr_copy.normal.stderr

@@ -25,5 +25,44 @@ note: called by `main`
 LL | pub fn main(i: f32, o: &mut f32) {
    |        ^^^^
 
-error: aborting due to 1 previous error
+error: cannot cast between pointer types
+       from `*f32`
+         to `*struct () {  }`
+  --> <$CORE_SRC/ptr/mod.rs>:630:9
+   |
+LL | /         ub_checks::assert_unsafe_precondition!(
+LL | |             check_language_ub,
+LL | |             "ptr::copy requires that both pointer arguments are aligned and non-null",
+...  |
+LL | |                 && ub_checks::maybe_is_aligned_and_not_null(dst, align, zero_size)
+LL | |         );
+   | |_________^
+   |
+note: used from within `core::ptr::copy::<f32>`
+  --> <$CORE_SRC/ptr/mod.rs>:630:9
+   |
+LL | /         ub_checks::assert_unsafe_precondition!(
+LL | |             check_language_ub,
+LL | |             "ptr::copy requires that both pointer arguments are aligned and non-null",
+...  |
+LL | |                 && ub_checks::maybe_is_aligned_and_not_null(dst, align, zero_size)
+LL | |         );
+   | |_________^
+note: called by `ptr_copy::copy_via_raw_ptr`
+  --> <$DIR/ptr_copy.rs>:29:18
+   |
+LL |         unsafe { core::ptr::copy(src, dst, 1) }
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: called by `ptr_copy::main`
+  --> <$DIR/ptr_copy.rs>:34:5
+   |
+LL |     copy_via_raw_ptr(&i, o);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+note: called by `main`
+  --> <$DIR/ptr_copy.rs>:33:8
+   |
+LL | pub fn main(i: f32, o: &mut f32) {
+   |        ^^^^
+
+error: aborting due to 2 previous errors