[clang][bytecode][NFC] Avoid a getSource() call (llvm#117311)

This is only needed when we actually emit a diagnostic, so move the
getSource() after the early return.

Author: tbaederr

clang/lib/AST/ByteCode/Interp.cpp

@@ -1481,11 +1481,12 @@ bool CheckNewTypeMismatch(InterpState &S, CodePtr OpPC, const Expr *E,
 
 bool InvalidNewDeleteExpr(InterpState &S, CodePtr OpPC, const Expr *E) {
   assert(E);
-  const auto &Loc = S.Current->getSource(OpPC);
 
   if (S.getLangOpts().CPlusPlus26)
     return true;
 
+  const auto &Loc = S.Current->getSource(OpPC);
+
   if (const auto *NewExpr = dyn_cast<CXXNewExpr>(E)) {
     const FunctionDecl *OperatorNew = NewExpr->getOperatorNew();