Prefix LOG and CHECK with AOS_

This prepares us for introducing glog more widely and transitioning
things over where they make sense.

Change-Id: Ic6c208882407bc2153fe875ffc736d66f5c8ade5
diff --git a/aos/protobuf/stack_arena_test.cc b/aos/protobuf/stack_arena_test.cc
index c9eb5e8..a07ceea 100644
--- a/aos/protobuf/stack_arena_test.cc
+++ b/aos/protobuf/stack_arena_test.cc
@@ -22,7 +22,7 @@
 
   TestStruct* msg =
       google::protobuf::Arena::Create<TestStruct>(stack_arena.arena());
-  CHECK_NOTNULL(msg);
+  AOS_CHECK_NOTNULL(msg);
 }
 
 }  // namespace