objtool/rust: add one more `noreturn` Rust function

objtool/rust: add one more `noreturn` Rust function

Between Rust 1.79 and 1.86, under `CONFIG_RUST_KERNEL_DOCTESTS=y`,
`objtool` may report:

    rust/doctests_kernel_generated.o: warning: objtool:
    rust_doctest_kernel_alloc_kbox_rs_13() falls through to next
    function rust_doctest_kernel_alloc_kvec_rs_0()

(as well as in rust_doctest_kernel_alloc_kvec_rs_0) due to calls to the
`noreturn` symbol:

    core::option::expect_failed

from code added in commits 779db37373a3 ("rust: alloc: kvec: implement
AsPageIter for VVec") and 671618432f46 ("rust: alloc: kbox: implement
AsPageIter for VBox").

Thus add the mangled one to the list so that `objtool` knows it is
actually `noreturn`.

This can be reproduced as well in other versions by tweaking the code,
such as the latest stable Rust (1.90.0).

Stable does not have code that triggers this, but it could have it in
the future. Downstream forks could too. Thus tag it for backport.

See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions")
for more details.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later.
Link: https://patch.msgid.link/20251020020714.2511718-1-ojeda@kernel.org