Add explicit dep on services.backup

android_robolectric_test is having some implicit deps removed
from it, so add in what we depend on directly.

Test: m RunFrameworksServicesRoboTests
Change-Id: Ice2abeb3f4d031cfe15ce919b750d6de59316c1f
Merged-In: Ice2abeb3f4d031cfe15ce919b750d6de59316c1f
diff --git a/services/robotests/Android.bp b/services/robotests/Android.bp
index 17d0bbf..566e61e 100644
--- a/services/robotests/Android.bp
+++ b/services/robotests/Android.bp
@@ -43,6 +43,7 @@
     // Include the testing libraries
     libs: [
         "platform-test-annotations",
+        "services.backup",
         "testng",
     ],