Attempt to run manifest generator continuously as unit tests

Change-Id: I264cd49f382a97cecdb86a86ad8f299c292ab42a
Test: presubmit
Bug: 180736967
diff --git a/tools/manifest-generator/tests/Android.bp b/tools/manifest-generator/tests/Android.bp
index c164c35..fd7a08e 100644
--- a/tools/manifest-generator/tests/Android.bp
+++ b/tools/manifest-generator/tests/Android.bp
@@ -21,8 +21,11 @@
 
     srcs: ["src/**/*.java"],
 
-    libs: [
+    static_libs: [
         "compatibility-manifest-generator",
         "junit",
     ],
+    test_options: {
+        unit_test: true,
+    },
 }