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/control_loops/drivetrain/distance_spline.h b/frc971/control_loops/drivetrain/distance_spline.h
index 63156fe..5c404a0 100644
--- a/frc971/control_loops/drivetrain/distance_spline.h
+++ b/frc971/control_loops/drivetrain/distance_spline.h
@@ -11,9 +11,7 @@
 #include "frc971/control_loops/drivetrain/trajectory_generated.h"
 #include "frc971/control_loops/fixed_quadrature.h"
 
-namespace frc971 {
-namespace control_loops {
-namespace drivetrain {
+namespace frc971::control_loops::drivetrain {
 
 std::vector<Spline> FlatbufferToSplines(const MultiSpline *fb);
 
@@ -127,8 +125,6 @@
   absl::Span<const float> distances_;
 };
 
-}  // namespace drivetrain
-}  // namespace control_loops
-}  // namespace frc971
+}  // namespace frc971::control_loops::drivetrain
 
 #endif  // FRC971_CONTROL_LOOPS_DRIVETRAIN_DISTANCE_SPLINE_H_