compiler: Directly use rustc_abi in const_eval

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -1,9 +1,9 @@
 // Not in interpret to make sure we do not use private implementation details
 
+use rustc_abi::VariantIdx;
 use rustc_middle::query::{Key, TyCtxtAt};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, mir};
-use rustc_target::abi::VariantIdx;
 use tracing::instrument;
 
 use crate::interpret::InterpCx;