Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/aos/ipc_lib/queue_racer.h b/aos/ipc_lib/queue_racer.h
index f0a2684..2cbe3ed 100644
--- a/aos/ipc_lib/queue_racer.h
+++ b/aos/ipc_lib/queue_racer.h
@@ -5,8 +5,7 @@
 
 #include "aos/ipc_lib/lockless_queue.h"
 
-namespace aos {
-namespace ipc_lib {
+namespace aos::ipc_lib {
 
 struct ThreadState;
 
@@ -97,7 +96,6 @@
                         size_t) { return true; };
 };
 
-}  // namespace ipc_lib
-}  // namespace aos
+}  // namespace aos::ipc_lib
 
 #endif  // AOS_IPC_LIB_QUEUE_RACER_H_