Implement virtual dispatch.  :-) This is self-consistent with clang,
but not yet necessarily perfectly consistent with gcc.  Also addressed
Doug and John's comments.

llvm-svn: 80137
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 4fc6c7c..e8f0cc5 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -826,6 +826,8 @@
                   const Decl *TargetDecl = 0);
   RValue EmitCallExpr(const CallExpr *E);
   
+  llvm::Value *BuildVirtualCall(const CXXMethodDecl *MD, llvm::Value *&This,
+                                const llvm::Type *Ty);
   RValue EmitCXXMemberCall(const CXXMethodDecl *MD,
                            llvm::Value *Callee,
                            llvm::Value *This,