remove no longer used import

Author: Jared-Prime

clippy_lints/src/exit.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint;
 use rustc_hir::{Expr, ExprKind, Item, ItemKind, OwnerNode};
-use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;