Stabilize std::num

This commit stabilizes the `std::num` module:

* The `Int` and `Float` traits are deprecated in favor of (1) the
  newly-added inherent methods and (2) the generic traits available in
  rust-lang/num.

* The `Zero` and `One` traits are reintroduced in `std::num`, which
  together with various other traits allow you to recover the most
  common forms of generic programming.

* The `FromStrRadix` trait, and associated free function, is deprecated
  in favor of inherent implementations.

* A wide range of methods and constants for both integers and floating
  point numbers are now `#[stable]`, having been adjusted for integer
  guidelines.

* `is_positive` and `is_negative` are renamed to `is_sign_positive` and
  `is_sign_negative`, in order to address #22985

* The `Wrapping` type is moved to `std::num` and stabilized;
  `WrappingOps` is deprecated in favor of inherent methods on the
  integer types, and direct implementation of operations on
  `Wrapping<X>` for each concrete integer type `X`.

Closes #22985
Closes #21069

[breaking-change]

1 files changed, 0 insertions, 1 deletions

diff --git a/src/liballoc/heap.rs b/src/liballoc/heap.rs
index 3733350412e..a2adef60cb1 100644
--- a/src/liballoc/heap.rs
+++ b/src/liballoc/heap.rs
@@ -189,7 +189,6 @@ mod imp {
     use core::option::Option;
     use core::option::Option::None;
     use core::ptr::{null_mut, null};
-    use core::num::Int;
     use libc::{c_char, c_int, c_void, size_t};
     use super::MIN_ALIGN;