Add master build of next Art version (Android T)

Built from commit e208b04cc2efaf707390d7acbe8f978142701d72.

Bug: 217158412
Change-Id: Ic9c473cd6b7d0032b4b8299938ca42294a210b43
diff --git a/build.gradle b/build.gradle
index 7f4bcb1..02f53e1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -387,6 +387,7 @@
                 "linux/art-9.0.0",
                 "linux/art-10.0.0",
                 "linux/host/art-12.0.0-beta4",
+                "linux/host/art-13-master",
                 "linux/dalvik",
                 "linux/dalvik-4.0.4",
                 "${osString}/dx",