Add support for a prebuilt_root_host type.

Test: art-tests
Change-Id: If013e46d2bbd9cc937a11fe7cf3b67eb8b262b55
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index 377a566..a142833 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -54,6 +54,7 @@
 	ctx.RegisterModuleType("prebuilt_etc", PrebuiltEtcFactory)
 	ctx.RegisterModuleType("prebuilt_etc_host", PrebuiltEtcHostFactory)
 	ctx.RegisterModuleType("prebuilt_root", PrebuiltRootFactory)
+	ctx.RegisterModuleType("prebuilt_root_host", PrebuiltRootHostFactory)
 	ctx.RegisterModuleType("prebuilt_usr_share", PrebuiltUserShareFactory)
 	ctx.RegisterModuleType("prebuilt_usr_share_host", PrebuiltUserShareHostFactory)
 	ctx.RegisterModuleType("prebuilt_font", PrebuiltFontFactory)
@@ -454,6 +455,17 @@
 	return module
 }
 
+// prebuilt_root_host is for a host prebuilt artifact that is installed in $(HOST_OUT)/<sub_dir>
+// directory.
+func PrebuiltRootHostFactory() android.Module {
+	module := &PrebuiltEtc{}
+	InitPrebuiltEtcModule(module, ".")
+	// This module is host-only
+	android.InitAndroidArchModule(module, android.HostSupported, android.MultilibCommon)
+	android.InitDefaultableModule(module)
+	return module
+}
+
 // prebuilt_usr_share is for a prebuilt artifact that is installed in
 // <partition>/usr/share/<sub_dir> directory.
 func PrebuiltUserShareFactory() android.Module {