Mark the new fmt impls with the correct rust version

Author: rick-de-water

library/core/src/num/nonzero.rs

@@ -110,8 +110,8 @@ impl_zeroable_primitive!(
 pub struct NonZero<T: ZeroablePrimitive>(T::NonZeroInner);
 
 macro_rules! impl_nonzero_fmt {
-    ($Trait:ident) => {
-        #[stable(feature = "nonzero", since = "1.28.0")]
+    ($Trait:ident, $Feature:literal, $Since:literal) => {
+        #[stable(feature = $Feature, since = $Since)]
         impl<T> fmt::$Trait for NonZero<T>
         where
             T: ZeroablePrimitive + fmt::$Trait,
@@ -124,14 +124,14 @@ macro_rules! impl_nonzero_fmt {
     };
 }
 
-impl_nonzero_fmt!(Debug);
-impl_nonzero_fmt!(Display);
-impl_nonzero_fmt!(Binary);
-impl_nonzero_fmt!(Octal);
-impl_nonzero_fmt!(LowerHex);
-impl_nonzero_fmt!(UpperHex);
-impl_nonzero_fmt!(LowerExp);
-impl_nonzero_fmt!(UpperExp);
+impl_nonzero_fmt!(Debug, "nonzero", "1.28.0");
+impl_nonzero_fmt!(Display, "nonzero", "1.28.0");
+impl_nonzero_fmt!(Binary, "nonzero", "1.28.0");
+impl_nonzero_fmt!(Octal, "nonzero", "1.28.0");
+impl_nonzero_fmt!(LowerHex, "nonzero", "1.28.0");
+impl_nonzero_fmt!(UpperHex, "nonzero", "1.28.0");
+impl_nonzero_fmt!(LowerExp, "nonzero_fmt_exp", "CURRENT_RUSTC_VERSION");
+impl_nonzero_fmt!(UpperExp, "nonzero_fmt_exp", "CURRENT_RUSTC_VERSION");
 
 macro_rules! impl_nonzero_auto_trait {
     (unsafe $Trait:ident) => {