ion-unit-tests: Add system heap presence test

Make sure system heap is present on devices, its id is '0',
and that we can allocate and free buffers from the system heap

Bug: 140507100
Fixes: 140507100
Tests: ion-unit-tests --gtest_fiter=SystemHeap.*

Change-Id: Ief502c9fce1e54f54b4e6d60f288954e4bf42e04
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/libion/tests/Android.bp b/libion/tests/Android.bp
index d3b4688..5600702 100644
--- a/libion/tests/Android.bp
+++ b/libion/tests/Android.bp
@@ -24,7 +24,8 @@
     srcs: [
         "allocate_test.cpp",
         "exit_test.cpp",
-    	"heap_query.cpp",
+        "heap_query.cpp",
+        "system_heap.cpp",
         "invalid_values_test.cpp",
         "ion_test_fixture.cpp",
         "map_test.cpp",