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

llvm/lib/IR/DIBuilder.cpp

@@ -55,7 +55,7 @@ public:
     return HeaderBuilder().concat("0x" + Twine::utohexstr(Tag));
   }
 };
-}
+} // namespace
 
 DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes)
     : M(m), VMContext(M.getContext()), TempEnumTypes(nullptr),