Fix norem_div examples

Author: newpavlov

library/core/src/num/int_macros.rs

@@ -1142,11 +1142,11 @@ macro_rules! int_impl {
         ///
         /// ```should_panic
         /// #![feature(norem_div)]
-        #[doc = concat!("129", stringify!($SelfT), ".norem_div(2);")]
+        #[doc = concat!("let _ = 129", stringify!($SelfT), ".norem_div(2);")]
         /// ```
         /// ```should_panic
         /// #![feature(norem_div)]
-        #[doc = concat!(stringify!($SelfT), "::MIN.norem_div(-1);")]
+        #[doc = concat!("let _ = ", stringify!($SelfT), "::MIN.norem_div(-1);")]
         /// ```
         #[unstable(
             feature = "norem_div",

library/core/src/num/uint_macros.rs

@@ -1050,7 +1050,7 @@ macro_rules! uint_impl {
         ///
         /// ```should_panic
         /// #![feature(norem_div)]
-        #[doc = concat!("129", stringify!($SelfT), ".norem_div(2);")]
+        #[doc = concat!("let _ = 129", stringify!($SelfT), ".norem_div(2);")]
         /// ```
         #[unstable(
             feature = "norem_div",