prebuilt_etc is OutputFileProducer

This allows us to add prebuilt_etc modules to the properties like
java_test_host.data

Bug: N/A
Test: atest VirtualizationHostTestCases
Change-Id: Id4f691ff324daa86b25f32599b62edfaebed1a7d
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index 850c8f9..57563eb 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -28,6 +28,8 @@
 // various `prebuilt_*` mutators.
 
 import (
+	"fmt"
+
 	"github.com/google/blueprint/proptools"
 
 	"android/soong/android"
@@ -208,6 +210,17 @@
 	return p.outputFilePath
 }
 
+var _ android.OutputFileProducer = (*PrebuiltEtc)(nil)
+
+func (p *PrebuiltEtc) OutputFiles(tag string) (android.Paths, error) {
+	switch tag {
+	case "":
+		return android.Paths{p.outputFilePath}, nil
+	default:
+		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
+	}
+}
+
 func (p *PrebuiltEtc) SubDir() string {
 	if subDir := proptools.String(p.properties.Sub_dir); subDir != "" {
 		return subDir