[PATCH 5/7] rust: init: add `..Zeroable::zeroed()` syntax for zeroing all missing fields

[Alice Ryhl]

Benno Lossin <benno.lossin@xxxxxxxxx> writes:
> Add the struct update syntax to the init macros, but only for
> `..Zeroable::zeroed()`. Adding this at the end of the struct initializer
> allows one to omit fields from the initializer, these fields will be
> initialized with 0x00 set to every byte. Only types that implement the
> `Zeroable` trait can utilize this.
> 
> Suggested-by: Asahi Lina <lina@xxxxxxxxxxxxx>
> Signed-off-by: Benno Lossin <benno.lossin@xxxxxxxxx>

I'm a bit surprised by how large this change is, but it looks ok.

Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>