[AST] Make ArrayTypeTraitExpr non-polymorphic.

[riccibruno]

Summary

ArrayTypeTraitExpr is the only expression class which is polymorphic.
As far as I can tell this is completely pointless.

[aaron.ballman]

LGTM!

cfe/trunk/include/clang/AST/ExprCXX.h

class ArrayTypeTraitExpr : public Expr {
   SourceLocation Loc;
 
   /// The location of the closing paren.
   SourceLocation RParen;
 
   /// The type being queried.
   TypeSourceInfo *QueriedType = nullptr;
 
-  virtual void anchor();
-
 public:
   friend class ASTStmtReader;
 
   ArrayTypeTraitExpr(SourceLocation loc, ArrayTypeTrait att,
                      TypeSourceInfo *queried, uint64_t value,
                      Expr *dimension, SourceLocation rparen, QualType ty)
       : Expr(ArrayTypeTraitExprClass, ty, VK_RValue, OK_Ordinary,
              false, queried->getType()->isDependentType(),
              (queried->getType()->isInstantiationDependentType() ||
               (dimension && dimension->isInstantiationDependent())),
              queried->getType()->containsUnexpandedParameterPack()),
         ATT(att), Value(value), Dimension(dimension),
         Loc(loc), RParen(rparen), QueriedType(queried) {}
 
   explicit ArrayTypeTraitExpr(EmptyShell Empty)
       : Expr(ArrayTypeTraitExprClass, Empty), ATT(0) {}
 
-  virtual ~ArrayTypeTraitExpr() = default;
-
   SourceLocation getBeginLoc() const LLVM_READONLY { return Loc; }
   SourceLocation getEndLoc() const LLVM_READONLY { return RParen; }
 
   ArrayTypeTrait getTrait() const { return static_cast<ArrayTypeTrait>(ATT); }
 
   QualType getQueriedType() const { return QueriedType->getType(); }
 
   TypeSourceInfo *getQueriedTypeSourceInfo() const { return QueriedType; }

cfe/trunk/lib/AST/ExprCXX.cpp

TypeTraitExpr *TypeTraitExpr::Create(const ASTContext &C, QualType T,
   return new (Mem) TypeTraitExpr(T, Loc, Kind, Args, RParenLoc, Value);
 }
 
 TypeTraitExpr *TypeTraitExpr::CreateDeserialized(const ASTContext &C,
                                                  unsigned NumArgs) {
   void *Mem = C.Allocate(totalSizeToAlloc<TypeSourceInfo *>(NumArgs));
   return new (Mem) TypeTraitExpr(EmptyShell());
 }
-
-void ArrayTypeTraitExpr::anchor() {}