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/frc971/orin/crcv_generator.cc b/frc971/orin/crcv_generator.cc
index 5c72385..a3f1f03 100644
--- a/frc971/orin/crcv_generator.cc
+++ b/frc971/orin/crcv_generator.cc
@@ -15,8 +15,8 @@
 // ahead-of-time optimized functions as directed by command-line arguments.
 // https://halide-lang.org/tutorials/tutorial_lesson_15_generators.html has an
 // introduction to much of the magic in this file.
-namespace frc971 {
-namespace orin {
+
+namespace frc971::orin {
 namespace {
 
 template <typename T>
@@ -142,8 +142,7 @@
   }
 };
 
-}  // namespace orin
-}  // namespace frc971
+}  // namespace frc971::orin
 
 HALIDE_REGISTER_GENERATOR(frc971::orin::YCbCr, ycbcr)
 HALIDE_REGISTER_GENERATOR(frc971::orin::YCbCr422, ycbcr422)