Finished moving backend-agnostic code to rustc_codegen_ssa

src/librustc_codegen_llvm/attributes.rs

@@ -21,7 +21,7 @@ use rustc::ty::query::Providers;
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_target::spec::PanicStrategy;
-use interfaces::*;
+use rustc_codegen_ssa::interfaces::*;
 
 use attributes;
 use llvm::{self, Attribute};