Install data_libs using relative_install_path property

Test: Added to data_libs tests
Test: Manually verified with bionic-unit-tests
Test: Treehugger
Change-Id: I28a8e08e3409f1e7c7bb72f4351310b57f35f513
diff --git a/apex/androidmk.go b/apex/androidmk.go
index b9bcc3a..10cc4b6 100644
--- a/apex/androidmk.go
+++ b/apex/androidmk.go
@@ -116,9 +116,9 @@
 			if len(fi.symlinks) > 0 {
 				fmt.Fprintln(w, "LOCAL_MODULE_SYMLINKS :=", strings.Join(fi.symlinks, " "))
 			}
-			newDataPaths := []android.Path{}
+			newDataPaths := []android.DataPath{}
 			for _, path := range fi.dataPaths {
-				dataOutPath := modulePath + ":" + path.Rel()
+				dataOutPath := modulePath + ":" + path.SrcPath.Rel()
 				if ok := seenDataOutPaths[dataOutPath]; !ok {
 					newDataPaths = append(newDataPaths, path)
 					seenDataOutPaths[dataOutPath] = true