Removed some ignore warning markers added during debugging

Author: ndrewxie

compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical/dedup_solver.rs

@@ -1,8 +1,3 @@
-#![allow(unused_imports)]
-#![allow(unused_variables)]
-#![allow(dead_code)]
-#![allow(unreachable_code)]
-
 use crate::infer::canonical::QueryRegionConstraints;
 use crate::infer::region_constraints::MemberConstraint;
 use rustc_infer::infer::InferCtxt;