make linker_config OutputFileProducer

so that they can be used in `srcs` of genrule.

Bug: 181093750
Test: m
Change-Id: Ia54554f1e81d766a970c9c4e02906ef9c0d85934
diff --git a/linkerconfig/linkerconfig.go b/linkerconfig/linkerconfig.go
index 0ed7409..241cac6 100644
--- a/linkerconfig/linkerconfig.go
+++ b/linkerconfig/linkerconfig.go
@@ -17,6 +17,7 @@
 import (
 	"android/soong/android"
 	"android/soong/etc"
+	"fmt"
 
 	"github.com/google/blueprint/proptools"
 )
@@ -68,6 +69,17 @@
 	return l.outputFilePath
 }
 
+var _ android.OutputFileProducer = (*linkerConfig)(nil)
+
+func (l *linkerConfig) OutputFiles(tag string) (android.Paths, error) {
+	switch tag {
+	case "":
+		return android.Paths{l.outputFilePath}, nil
+	default:
+		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
+	}
+}
+
 func (l *linkerConfig) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	inputFile := android.PathForModuleSrc(ctx, android.String(l.properties.Src))
 	l.outputFilePath = android.PathForModuleOut(ctx, "linker.config.pb").OutputPath