Revert "Add rustc lint, warning when iterating over hashmaps"

compiler/rustc_codegen_llvm/src/lib.rs

@@ -13,7 +13,6 @@
 #![feature(iter_zip)]
 #![feature(nll)]
 #![recursion_limit = "256"]
-#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 use back::write::{create_informational_target_machine, create_target_machine};