Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
  -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
  llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
index 6351fa2..4c74182 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
@@ -180,6 +180,6 @@
     void EmitPhysRegCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap,
                          MachineBasicBlock::iterator InsertPos);
   };
-}
+} // namespace llvm
 
 #endif