#87 Patch to prevent compiler warning when building for 64-bit

[calzakk]

To avoid a compiler warning when building for 64-bit, could you change the XML_GetCurrentByteIndex function in xmlparse.c to the following (i.e. cast the subtraction):

XML_Index XMLCALL
XML_GetCurrentByteIndex(XML_Parser parser)
{
if (eventPtr)
return parseEndByteIndex - (XML_Index)(parseEndPtr - eventPtr);
return -1;
}

[Sebastian Pipping]

We have this code in by now:

return (XML_Index)(parseEndByteIndex - (parseEndPtr - eventPtr));

If you still get warnings, please open a new ticket or pull request at GitHub: https://github.com/libexpat/libexpat/issues/