[xml] xmlReportError returns

["Adrian Mouat" <adrianmouat metsoftpro com>]

 I was just looking at the code for  xmlReportError in error.c and I'm a bit
confused by the lines:

 if (code == XML_ERR_OK)
        return;

That appear all over the place. Under what circumstances will code have
changed?

Just curious; sorry if it's a stupid question!