remove unused import

Author: Saleem Jaffer

src/librustc_mir/hair/cx/expr.rs

@@ -8,7 +8,6 @@ use rustc::hir::def::{Def, CtorKind};
 use rustc::mir::interpret::{GlobalId, ErrorHandled};
 use rustc::ty::{self, AdtKind, Ty};
 use rustc::ty::adjustment::{Adjustment, Adjust, AutoBorrow, AutoBorrowMutability};
-use rustc::ty::cast::CastKind as TyCastKind;
 use rustc::hir;
 use rustc::hir::def_id::LocalDefId;
 use rustc::mir::BorrowKind;