Make the Kaleidoscope Orc examples -Wdeprecated clean by avoiding copying some AST nodes

llvm-svn: 249703
diff --git a/llvm/examples/Kaleidoscope/Orc/initial/toy.cpp b/llvm/examples/Kaleidoscope/Orc/initial/toy.cpp
index 8dab73b..085d0da 100644
--- a/llvm/examples/Kaleidoscope/Orc/initial/toy.cpp
+++ b/llvm/examples/Kaleidoscope/Orc/initial/toy.cpp
@@ -781,7 +781,7 @@
   // Special case '=' because we don't want to emit the LHS as an expression.
   if (Op == '=') {
     // Assignment requires the LHS to be an identifier.
-    auto LHSVar = static_cast<VariableExprAST&>(*LHS);
+    auto &LHSVar = static_cast<VariableExprAST &>(*LHS);
     // Codegen the RHS.
     Value *Val = RHS->IRGen(C);
     if (!Val) return nullptr;