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/logging/log_namer.cc b/aos/logging/log_namer.cc
index 4e9e00e..16ba0f2 100644
--- a/aos/logging/log_namer.cc
+++ b/aos/logging/log_namer.cc
@@ -33,8 +33,7 @@
               "The folder to log to.  If empty, search for the /media/sd*1/ "
               "folder and place logs there.");
 
-namespace aos {
-namespace logging {
+namespace aos::logging {
 namespace {
 void AllocateLogName(char **filename, const char *directory,
                      const char *basename) {
@@ -187,5 +186,4 @@
   return log_base_name.value();
 }
 
-}  // namespace logging
-}  // namespace aos
+}  // namespace aos::logging