Memory leak in UPCEANExtension2Support.decodeRow

After apply #142

file: ZXing.OneD.UPCEANExtension2Support
line: 110

current:

```
  if (extensionData <> nil)
  then
     extensionResult.putAllMetadata(extensionData);
```

should be:

```
  if (extensionData <> nil) then
  begin
    extensionResult.putAllMetadata(extensionData);
    FreeAndNil(extensionData);
  end;
```