metadata: Encode attrs for foreign items.

Related to #19649 and #16289

Author: tomjakubowski

src/librustc/metadata/encoder.rs

@@ -1478,6 +1478,7 @@ fn encode_info_for_foreign_item(ecx: &EncodeContext,
         if abi == abi::RustIntrinsic {
             encode_inlined_item(ecx, rbml_w, IIForeignRef(nitem));
         }
+        encode_attributes(rbml_w, &*nitem.attrs);
         encode_symbol(ecx, rbml_w, nitem.id);
       }
       ast::ForeignItemStatic(_, mutbl) => {
@@ -1488,6 +1489,7 @@ fn encode_info_for_foreign_item(ecx: &EncodeContext,
         }
         encode_bounds_and_type(rbml_w, ecx,
                                &lookup_item_type(ecx.tcx,local_def(nitem.id)));
+        encode_attributes(rbml_w, &*nitem.attrs);
         encode_symbol(ecx, rbml_w, nitem.id);
         encode_name(rbml_w, nitem.ident.name);
       }