Remove the last virtual member function from the Decl hierarchy,

reducing the size of all declarations by one pointer. For a 64-bit
Clang parsing Cocoa.h, this saves ~630k of memory (about 3.5% of
ASTContext's memory usage for this header).

llvm-svn: 125756

clang/include/clang/AST/DeclBase.h

@@ -270,8 +270,6 @@ protected:
     if (Decl::CollectingStats()) add(DK);
   }
 
-  virtual ~Decl();
-  
 public:
 
   /// \brief Source range that this declaration covers.

clang/lib/AST/DeclBase.cpp

@@ -288,9 +288,6 @@ void PrettyStackTraceDecl::print(llvm::raw_ostream &OS) const {
 // Decl Implementation
 //===----------------------------------------------------------------------===//
 
-// Out-of-line virtual method providing a home for Decl.
-Decl::~Decl() { }
-
 bool Decl::isOutOfLine() const {
   if (const VarDecl *VD = dyn_cast<VarDecl>(this))
     return VD->isOutOfLine();