add a rustc::query_stability lint

compiler/rustc_codegen_ssa/src/lib.rs

@@ -7,6 +7,7 @@
 #![feature(nll)]
 #![feature(associated_type_bounds)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).
 //! The backend-agnostic functions of this crate use functions defined in various traits that