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/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 1e20807..d3d2fcd 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -65,7 +65,7 @@
     P.first->dropAllReferences();
   }
 };
-}
+} // namespace
 
 LLVMContextImpl::~LLVMContextImpl() {
   // NOTE: We need to delete the contents of OwnedModules, but Module's dtor
@@ -199,7 +199,7 @@
 /// does not cause MDOperand to be transparent.  In particular, a bare pointer
 /// doesn't get hashed before it's combined, whereas \a MDOperand would.
 static const Metadata *get_hashable_data(const MDOperand &X) { return X.get(); }
-}
+} // namespace llvm
 
 unsigned MDNodeOpsKey::calculateHash(MDNode *N, unsigned Offset) {
   unsigned Hash = hash_combine_range(N->op_begin() + Offset, N->op_end());