Rollup merge of rust-lang#103570 - lukas-code:stabilize-ilog, r=scottmcm

Stabilize integer logarithms

Stabilizes feature `int_log`.

I've also made the functions const stable, because they don't depend on any unstable const features. `rustc_allow_const_fn_unstable` is just there for `Option::expect`, which could be replaced with a `match` and `panic!`. cc ``@rust-lang/wg-const-eval``

closes rust-lang#70887 (tracking issue)

~~blocked on FCP finishing: rust-lang#70887 (comment)
FCP finished: rust-lang#70887 (comment)

Author: Dylan-DPC

src/lib.rs

@@ -3,7 +3,6 @@
 #![feature(never_type)]
 #![feature(try_blocks)]
 #![feature(io_error_more)]
-#![feature(int_log)]
 #![feature(variant_count)]
 #![feature(yeet_expr)]
 #![feature(is_some_and)]

tests/pass/integer-ops.rs

@@ -1,5 +1,4 @@
 //@compile-flags: -Coverflow-checks=off
-#![feature(int_log)]
 #![allow(arithmetic_overflow)]
 
 pub fn main() {