Revert r194865 and r194874.

This change is incorrect. If you delete virtual destructor of both a base class
and a subclass, then the following code:
  Base *foo = new Child();
  delete foo;
will not cause the destructor for members of Child class. As a result, I observe
plently of memory leaks. Notable examples I investigated are:
ObjectBuffer and ObjectBufferStream, AttributeImpl and StringSAttributeImpl.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194997 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/YAMLParser.cpp

@@ -96,15 +96,6 @@ static EncodingInfo getUnicodeEncoding(StringRef Input) {
 
 namespace llvm {
 namespace yaml {
-/// pin the vtables to this file
-void Node::anchor() {}
-void NullNode::anchor() {}
-void ScalarNode::anchor() {}
-void KeyValueNode::anchor() {}
-void MappingNode::anchor() {}
-void SequenceNode::anchor() {}
-void AliasNode::anchor() {}
-
 /// Token - A single YAML token.
 struct Token : ilist_node<Token> {
   enum TokenKind {