Fix mismatched new/delete warning

Change-Id: I3dabc9d3c5d84693724f3dacc68956f89c17ec9e
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>

src/plugins/imageformats/macjp2/qiiofhelpers.cpp

@@ -74,7 +74,7 @@ static off_t cbSkipForward(void *info, off_t count)
     } else {
         char *buf = new char[count];
         res = dev->read(buf, count);
-        delete buf;
+        delete[] buf;
     }
     return qMax(qint64(0), res);
 }