[harbour-barcode] Fixed BitMatrix leak

In case if GlobalHistogramBinarizer::getBlackMatrix() throws an exception
like this:

  #0 zxing::Exception::Exception () at Exception.h:34
  #1 ReaderException::ReaderException () at ReaderException.h:30
  #2 NotFoundException::NotFoundException () at NotFoundException.h:28
  #3 zxing::GlobalHistogramBinarizer::estimateBlackPoint() at GlobalHistogramBinarizer.cpp:198
  #4 zxing::GlobalHistogramBinarizer::getBlackMatrix () GlobalHistogramBinarizer.cpp:129
  #5 zxing::BinaryBitmap::getBlackMatrix () BinaryBitmap.cpp:40
  ...

src/zxing/zxing/common/GlobalHistogramBinarizer.cpp

@@ -103,7 +103,7 @@ Ref<BitMatrix> GlobalHistogramBinarizer::getBlackMatrix() {
     LuminanceSource& source = *getLuminanceSource();
     int width = source.getWidth();
     int height = source.getHeight();
-    BitMatrix* matrix = new BitMatrix(width, height);
+    Ref<BitMatrix> matrix(new BitMatrix(width, height));
 
     // Quickly calculates the histogram by sampling four rows from the image.
     // This proved to be more robust on the blackbox tests than sampling a
@@ -138,7 +138,7 @@ Ref<BitMatrix> GlobalHistogramBinarizer::getBlackMatrix() {
         }
     }
 
-    return Ref<BitMatrix>(matrix);
+    return matrix;
 }
 
 using namespace std;