Use depsets for transitive manifests and assets

Instead of rolling assets and manifests up through each static lib,
provide them as a DepSet.  This will help with the next patch, which
needs to pass all the transitive manifests and R.txt files together.

Test: app_test.go
Change-Id: Id8b3aa2bed3771e82ab6bde192c9b43baa38b54c

java/androidmk.go

@@ -368,8 +368,13 @@ func (app *AndroidApp) AndroidMkEntries() []android.AndroidMkEntries {
 
 				filterRRO := func(filter overlayType) android.Paths {
 					var paths android.Paths
-					for _, d := range app.rroDirs {
+					seen := make(map[android.Path]bool)
+					for _, d := range app.rroDirsDepSet.ToList() {
 						if d.overlayType == filter {
+							if seen[d.path] {
+								continue
+							}
+							seen[d.path] = true
 							paths = append(paths, d.path)
 						}
 					}