Unconditionally create SuperScale in BarcodeDetector to avoid null deref

This pointer is called unconditionally in BarcodeImpl::initDecode
assuming the size of the image is outside the specified bounds.  This
seems to not cause problems on optimized builds, I assume because the
optimizer sees through the processImageScale call to see that it can be
reduced to a resize call.  Leaving it as is relies on undefined
behavior.

This was the least invasive change I could make, however, it might be
worthwhile to pull up the logic for a resize so that a SuperScale does
not need to be allocated, which seems to be the most common case.

modules/objdetect/src/barcode.cpp

@@ -343,11 +343,11 @@ BarcodeDetector::BarcodeDetector(const string &prototxt_path, const string &mode
 {
     Ptr<BarcodeImpl> p_ = new BarcodeImpl();
     p = p_;
+    p_->sr = make_shared<SuperScale>();
     if (!prototxt_path.empty() && !model_path.empty())
     {
         CV_Assert(utils::fs::exists(prototxt_path));
         CV_Assert(utils::fs::exists(model_path));
-        p_->sr = make_shared<SuperScale>();
         int res = p_->sr->init(prototxt_path, model_path);
         CV_Assert(res == 0);
         p_->use_nn_sr = true;