!5 删除lite_subsystem模板，使用原生的gn group内置函数

Merge pull request !5 from jady3356/master

BUILD.gn

-# Copyright (c) 2020 Huawei Device Co., Ltd.
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
+# Copyright (c) 2020 Huawei Device Co., Ltd.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
 # limitations under the License.
-
-import("//build/lite/config/subsystem/lite_subsystem.gni")
-import("//build/lite/config/component/lite_component.gni")
-
-lite_subsystem("iot") {
-    subsystem_components = [
-        ":link"
-    ]
-}
-
-lite_component("link") {
-    features = [
-    ]
-}
+
+import("//build/lite/config/component/lite_component.gni")
+
+group("iot") {
+  deps = [ ":link" ]
+}
+
+lite_component("link") {
+  features = []
+}