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/frc971/wpilib/drivetrain_writer.h b/frc971/wpilib/drivetrain_writer.h
index 195b5a3..e83585e 100644
--- a/frc971/wpilib/drivetrain_writer.h
+++ b/frc971/wpilib/drivetrain_writer.h
@@ -6,8 +6,7 @@
 #include "frc971/wpilib/ahal/PWM.h"
 #include "frc971/wpilib/loop_output_handler.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 class DrivetrainWriter : public ::frc971::wpilib::LoopOutputHandler<
                              ::frc971::control_loops::drivetrain::Output> {
@@ -56,7 +55,6 @@
   bool reversed_right0_, reversed_left0_, reversed_right1_, reversed_left1_;
 };
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib
 
 #endif  // FRC971_WPILIB_DRIVETRAIN_WRITER_H_