Stabilize remaining integer methods as const fn

This includes the following functions:
- i*::checked_div
- i*::checked_div_euclid
- i*::checked_rem
- i*::checked_rem_euclid
- i*::div_euclid
- i*::overflowing_div
- i*::overflowing_div_euclid
- i*::overflowing_rem
- i*::overflowing_rem_euclid
- i*::rem_euclid
- i*::wrapping_div
- i*::wrapping_div_euclid
- i*::wrapping_rem
- i*::wrapping_rem_euclid
- u*::checked_div
- u*::checked_div_euclid
- u*::checked_rem
- u*::checked_rem_euclid
- u*::div_euclid
- u*::overflowing_div
- u*::overflowing_div_euclid
- u*::overflowing_rem
- u*::overflowing_rem_euclid
- u*::rem_euclid
- u*::wrapping_div
- u*::wrapping_div_euclid
- u*::wrapping_rem
- u*::wrapping_rem_euclid

src/test/ui/consts/const-int-arithmetic.rs

@@ -1,10 +1,5 @@
 // run-pass
 
-#![feature(const_checked_int_methods)]
-#![feature(const_euclidean_int_methods)]
-#![feature(const_overflowing_int_methods)]
-#![feature(const_wrapping_int_methods)]
-
 macro_rules! suite {
     ($(
         $fn:ident -> $ty:ty { $( $label:ident : $expr:expr, $result:expr; )* }