Remove unnecessary check for fat LTO

Author: bjorn3

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -998,7 +998,7 @@ fn execute_fat_lto_work_item<B: ExtraBackendMethods>(
     let mut module =
         B::run_fat_lto(cgcx, needs_fat_lto, import_only_modules).unwrap_or_else(|e| e.raise());
 
-    if cgcx.lto == Lto::Fat && !autodiff.is_empty() {
+    if !autodiff.is_empty() {
         let config = cgcx.config(ModuleKind::Regular);
         if let Err(err) = B::autodiff(cgcx, &module, autodiff, config) {
             err.raise();