ebmlmaster: fix leak when reading the next element in live mode

We revert the position to the beginning of the element and it will
not be used afterwards.

libebml2/ebmlmaster.c

@@ -418,6 +418,7 @@ static err_t ReadData(ebml_master *Element, struct stream *Input, const ebml_par
     {
         assert(SubElement!=NULL);
         Stream_Seek(Input,SubElement->ElementPosition,SEEK_SET);
+        NodeDelete((node*)SubElement); // forget about it, it will be read again later
     }
     return ERR_NONE;
 }