ivi-shell: implement surface_on_many_layer test

A surface can be added to many layers.
This test is implemented to test this use-case
and the correct behaviour of get_layers_under_surface
API.

Signed-off-by: Emre Ucan <eucan@de.adit-jv.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/tests/ivi-test.h b/tests/ivi-test.h
index 5cb4739..5706ed8 100644
--- a/tests/ivi-test.h
+++ b/tests/ivi-test.h
@@ -37,5 +37,6 @@
 #define IVI_TEST_LAYER_ID(i) (IVI_TEST_LAYER_ID_BASE + i)
 
 #define IVI_TEST_SURFACE_COUNT (3)
+#define IVI_TEST_LAYER_COUNT (3)
 
 #endif /* IVI_TEST_H */