Remove extern crate rustc_middle from rustc_const_eval.

This requires exporting the interpreter macros so they can be used with
`use crate::interpret::*`.

compiler/rustc_const_eval/src/util/caller_location.rs

@@ -1,4 +1,5 @@
 use rustc_hir::LangItem;
+use rustc_middle::bug;
 use rustc_middle::mir;
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::LayoutOf;

compiler/rustc_const_eval/src/util/check_validity_requirement.rs

@@ -1,3 +1,4 @@
+use rustc_middle::bug;
 use rustc_middle::ty::layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout, ValidityRequirement};
 use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_target::abi::{Abi, FieldsShape, Scalar, Variants};

compiler/rustc_const_eval/src/util/type_name.rs

@@ -1,6 +1,7 @@
 use rustc_data_structures::intern::Interned;
 use rustc_hir::def_id::CrateNum;
 use rustc_hir::definitions::DisambiguatedDefPathData;
+use rustc_middle::bug;
 use rustc_middle::ty::{
     self,
     print::{PrettyPrinter, Print, PrintError, Printer},