Auto merge of #1213 - lcnr:master, r=RalfJung

rm custom `intrinsics::discriminant_value`

@RalfJung requires https://github.com/rust-lang/rust/pull/69825

src/shims/intrinsics.rs

@@ -248,12 +248,6 @@ fn call_intrinsic(
                 }
             }
 
-            "discriminant_value" => {
-                let place = this.deref_operand(args[0])?;
-                let discr_val = this.read_discriminant(place.into())?.0;
-                this.write_scalar(Scalar::from_uint(discr_val, dest.layout.size), dest)?;
-            }
-
             #[rustfmt::skip]
             | "sinf32"
             | "fabsf32"