Add Saturating type (based on Wrapping type)

Author: kellerkindt

library/core/src/num/mod.rs

@@ -43,8 +43,12 @@ mod uint_macros; // import uint_impl!
 mod error;
 mod int_log10;
 mod nonzero;
+#[unstable(feature = "saturating_int_impl", issue = "87920")]
+mod saturating;
 mod wrapping;
 
+#[unstable(feature = "saturating_int_impl", issue = "87920")]
+pub use saturating::Saturating;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use wrapping::Wrapping;