objdetect: crash in QR code test

[Nightly build (Win64 debug)](http://pullrequest.opencv.org/buildbot/builders/3_4_noOCL_noICV_noSSE-win64-vc14-debug/builds/520)

```
[----------] 5 tests from Objdetect_QRCode_Close
[ RUN      ] Objdetect_QRCode_Close.regression/0, where GetParam() = "close_1.png"
Process returned: -1073740791
```