Rename HandlerInner::delay_span_bug as HandlerInner::span_delayed_bug.

Because the corresponding `Level` is `DelayedBug` and `span_delayed_bug`
follows the pattern used everywhere else: `span_err`, `span_warning`,
etc.

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -91,7 +91,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                 Some(tcx.fn_sig(did))
             } else {
                 tcx.sess
-                    .delay_span_bug(attr.span, "this attribute can only be applied to functions");
+                    .span_delayed_bug(attr.span, "this attribute can only be applied to functions");
                 None
             }
         };