RS native tests should be built with clang.

Change-Id: I6f3bf8c138debe62be7fe8fe9d4d3339eb21a25b
diff --git a/tests/cppbasic/Android.mk b/tests/cppbasic/Android.mk
index bf7725a..3b19db7 100644
--- a/tests/cppbasic/Android.mk
+++ b/tests/cppbasic/Android.mk
@@ -30,6 +30,7 @@
 LOCAL_C_INCLUDES += frameworks/rs
 LOCAL_C_INCLUDES += $(intermediates)
 
+LOCAL_CLANG := true
 
 include $(BUILD_EXECUTABLE)