Add preparers for sysprop

Bug: 181070625
Test: m nothing
Change-Id: I3c9c36e7270b68ff7d354acb239b47441335a931

sysprop/Android.bp

@@ -14,6 +14,7 @@ bootstrap_go_package {
     ],
     srcs: [
         "sysprop_library.go",
+        "testing.go",
     ],
     testSrcs: [
         "sysprop_test.go",

sysprop/sysprop_library.go

@@ -193,7 +193,11 @@ func SyspropLibraries(config android.Config) []string {
 }
 
 func init() {
-	android.RegisterModuleType("sysprop_library", syspropLibraryFactory)
+	registerSyspropBuildComponents(android.InitRegistrationContext)
+}
+
+func registerSyspropBuildComponents(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("sysprop_library", syspropLibraryFactory)
 }
 
 func (m *syspropLibrary) Name() string {

sysprop/testing.go

@@ -0,0 +1,19 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// 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.
+
+package sysprop
+
+import "android/soong/android"
+
+var PrepareForTestWithSyspropBuildComponents = android.FixtureRegisterWithContext(registerSyspropBuildComponents)