clean up target feature system; most of the toggleability is now handled by the ABI target feature check

compiler/rustc_middle/src/query/mod.rs

@@ -2355,7 +2355,7 @@ rustc_queries! {
     }
 
     /// Returns the Rust target features for the current target. These are not always the same as LLVM target features!
-    query rust_target_features(_: CrateNum) -> &'tcx UnordMap<String, rustc_target::target_features::StabilityComputed> {
+    query rust_target_features(_: CrateNum) -> &'tcx UnordMap<String, rustc_target::target_features::Stability> {
         arena_cache
         eval_always
         desc { "looking up Rust target features" }