Add latest gmscore build to x20 dependencies.

Bug:
Change-Id: I6c1570affcef9d332b7e05c8a59719f6b920d9cb
diff --git a/build.gradle b/build.gradle
index f85dd6b..f11c7ae 100644
--- a/build.gradle
+++ b/build.gradle
@@ -152,6 +152,7 @@
         "gmscore/v8.tar.gz",
         "gmscore/gmscore_v9.tar.gz",
         "gmscore/gmscore_v10.tar.gz",
+        "gmscore/latest.tar.gz",
         "photos/2017-06-06.tar.gz",
         "youtube/youtube.android_11.47.tar.gz",
         "youtube/youtube.android_12.10.tar.gz",