Build CtsLibcoreTestCases into mts-art.

Test: m mts
Bug: 185422793
Change-Id: Ia6805b67946b2451ff0ce3c238bf8dec8cb112fb
diff --git a/tests/libcore/luni/Android.bp b/tests/libcore/luni/Android.bp
index 47f0faa..2fc1f56 100644
--- a/tests/libcore/luni/Android.bp
+++ b/tests/libcore/luni/Android.bp
@@ -61,7 +61,7 @@
     // Tag this module as a cts test artifact
     test_suites: [
         "cts",
-        "mts",
+        "mts-art",
         "general-tests",
     ],
 }