[test] TEST_MAPPING for incremental service

BUG: 172866626
Test: presubmit test; atest
Change-Id: If5a018028f83d44a71585173842c8535be2288b9
diff --git a/services/incremental/Android.bp b/services/incremental/Android.bp
index 7e1e99f..5ffbd77 100644
--- a/services/incremental/Android.bp
+++ b/services/incremental/Android.bp
@@ -133,5 +133,8 @@
     ],
     static_libs: [
         "libgmock",
-    ]
+    ],
+    test_options: {
+        unit_test: true,
+    },
 }