Add a test to invoke ion_is_using_modular_heaps()

Bug: 140916230
Test: ./ion-unit-tests

Change-Id: I0204b72e49f34d99df96b46229dda2e958a59bee
diff --git a/libion/tests/Android.bp b/libion/tests/Android.bp
index 5600702..989e029 100644
--- a/libion/tests/Android.bp
+++ b/libion/tests/Android.bp
@@ -29,5 +29,6 @@
         "invalid_values_test.cpp",
         "ion_test_fixture.cpp",
         "map_test.cpp",
+        "modular_heap_check.cpp",
     ],
 }