Parallelize singleton execution

Bug: 281536768
Test: manual, presubmits
Change-Id: I57fdc76ba6b277e88e196b506af87127a530fd37
diff --git a/android/gen_notice.go b/android/gen_notice.go
index 091345b..1acc638 100644
--- a/android/gen_notice.go
+++ b/android/gen_notice.go
@@ -28,7 +28,7 @@
 
 // Register the gen_notice module type.
 func RegisterGenNoticeBuildComponents(ctx RegistrationContext) {
-	ctx.RegisterSingletonType("gen_notice_build_rules", GenNoticeBuildRulesFactory)
+	ctx.RegisterParallelSingletonType("gen_notice_build_rules", GenNoticeBuildRulesFactory)
 	ctx.RegisterModuleType("gen_notice", GenNoticeFactory)
 }