Assemble ROOT/ files of target_files.zip

rsync will be used to copy the root files of the system_image dep

Test: verified that ROOT/ in target_files.zip is same when built with
make and soong
Bug: 385383524

Change-Id: I84279109308d36ec147a63000bb1912c2ffb1273
diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index 64b7931..b112568 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -459,6 +459,7 @@
 		FileListFile: fileListFile,
 		RootDir:      rootDir,
 	})
+
 	f.fileListFile = fileListFile
 
 	if proptools.Bool(f.properties.Unchecked_module) {