Enable building without sync

This is needed because the linux node binding needs to work without sync

binding.gyp

@@ -32,7 +32,7 @@
     },
     {
       "target_name": "object-store",
-      "dependencies": [ "realm-core", "realm-sync" ],
+      "dependencies": [ "realm-core" ],
       "type": "static_library",
       "include_dirs": [
         "src/object-store/src",
@@ -63,12 +63,6 @@
         "src/object-store/src/parser/query_builder.cpp",
         "src/object-store/src/util/format.cpp",
         "src/object-store/src/util/thread_id.cpp",
-        "src/object-store/src/sync/sync_manager.cpp",
-        "src/object-store/src/sync/sync_user.cpp",
-        "src/object-store/src/sync/sync_session.cpp",
-        "src/object-store/src/sync/impl/sync_file.cpp",
-        "src/object-store/src/sync/impl/sync_metadata.cpp",
-        "src/object-store/src/impl/apple/keychain_helper.cpp"
       ],
       "conditions": [
         ["OS=='linux'", {
@@ -80,6 +74,17 @@
           "sources": [
             "src/object-store/src/impl/apple/external_commit_helper.cpp"
           ]
+        }],
+        ["realm_enable_sync", {
+          "dependencies": [ "realm-sync" ],
+          "sources": [
+            "src/object-store/src/sync/sync_manager.cpp",
+            "src/object-store/src/sync/sync_user.cpp",
+            "src/object-store/src/sync/sync_session.cpp",
+            "src/object-store/src/sync/impl/sync_file.cpp",
+            "src/object-store/src/sync/impl/sync_metadata.cpp",
+            "src/object-store/src/impl/apple/keychain_helper.cpp"
+          ],
         }]
       ],
       "all_dependent_settings": {

src/js_realm.hpp

@@ -453,12 +453,15 @@ void RealmClass<T>::schema_version(ContextType ctx, ObjectType this_object, size
     }
 }
 
+
 template<typename T>
 void RealmClass<T>::clear_test_state(ContextType ctx, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
     validate_argument_count(argc, 0);
+#if REALM_ENABLE_SYNC
     for(auto &user : SyncManager::shared().all_users()) {
         user->log_out();
     }
+#endif
     delete_all_realms();
 }
 

src/node/gyp/realm.gyp

@@ -18,7 +18,7 @@
         ]
       },
       "all_dependent_settings": {
-        "defines": [ "REALM_HAVE_CONFIG", "REALM_PLATFORM_NODE=1", "REALM_ENABLE_SYNC=1" ]
+        "defines": [ "REALM_HAVE_CONFIG", "REALM_PLATFORM_NODE=1", "REALM_ENABLE_SYNC=<(realm_enable_sync)" ]
       },
       "variables": {
         "prefix": "<!(echo $REALM_CORE_PREFIX)"