Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/aos/starter/starterd_lib.cc b/aos/starter/starterd_lib.cc
index bf0fc31..95210c0 100644
--- a/aos/starter/starterd_lib.cc
+++ b/aos/starter/starterd_lib.cc
@@ -20,8 +20,7 @@
               "Number of threads to spin up to initialize the queue.  0 means "
               "use the main thread.");
 
-namespace aos {
-namespace starter {
+namespace aos::starter {
 
 const aos::Channel *StatusChannelForNode(const aos::Configuration *config,
                                          const aos::Node *node) {
@@ -315,5 +314,4 @@
           << shm_base_;
 }
 
-}  // namespace starter
-}  // namespace aos
+}  // namespace aos::starter