HACK: rust: pin-init: Disable references to previously initialized fields

aop_audio uses pin-init on `#[repr(C, packed)]` embedded into other
structs. This fails with "error[E0793]: reference to packed field is
unaligned" since packed struct have an alingment of 1 byte.

Fixes: 42415d1 ("rust: pin-init: add references to previously initialized fields")

Author: jannau

rust/pin-init/src/macros.rs

@@ -1353,8 +1353,8 @@ macro_rules! __init_internal {
         // - the field is not structurally pinned, since the line above must compile,
         // - the field has been initialized,
         // - the reference is only valid until the end of the initializer.
-        #[allow(unused_variables)]
-        let $field = unsafe { &mut (*$slot).$field };
+        // #[allow(unused_variables)]
+        // let $field = unsafe { &mut (*$slot).$field };
 
         // Create the drop guard:
         //
@@ -1395,7 +1395,7 @@ macro_rules! __init_internal {
         //   initializer,
         // - the field has been initialized,
         // - the reference is only valid until the end of the initializer.
-        let $field = unsafe { &mut (*$slot).$field };
+        // let $field = unsafe { &mut (*$slot).$field };
 
         // Create the drop guard:
         //