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/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 8274374..0264ad1 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -661,7 +661,7 @@
   }
 };
 
-}
+} // namespace
 
 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
   Type *Ty = SE.getEffectiveSCEVType(S->getType());
@@ -1933,7 +1933,7 @@
   }
   bool isDone() const { return IsUnsafe; }
 };
-}
+} // namespace
 
 namespace llvm {
 bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {