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/util/wrapping_counter.h b/aos/util/wrapping_counter.h
index ea79ec6..0353e2e 100644
--- a/aos/util/wrapping_counter.h
+++ b/aos/util/wrapping_counter.h
@@ -3,8 +3,7 @@
 
 #include <cstdint>
 
-namespace aos {
-namespace util {
+namespace aos::util {
 
 // Deals correctly with 1-byte counters which wrap.
 // This is only possible if the counter never wraps twice between Update calls.
@@ -28,7 +27,6 @@
   uint8_t last_count_;
 };
 
-}  // namespace util
-}  // namespace aos
+}  // namespace aos::util
 
 #endif  // AOS_UTIL_WRAPPING_COUNTER_H_