applied patch from Steve Ball to provide structured error reports.

* xmlreader.c, include/libxml/xmlreader.h: applied patch from
  Steve Ball to provide structured error reports.
diff --git a/include/libxml/xmlreader.h b/include/libxml/xmlreader.h
index f4add56..76499b8 100644
--- a/include/libxml/xmlreader.h
+++ b/include/libxml/xmlreader.h
@@ -304,6 +304,10 @@
 		    xmlTextReaderSetErrorHandler(xmlTextReaderPtr reader, 
 						 xmlTextReaderErrorFunc f, 
 						 void *arg);
+XMLPUBFUN void XMLCALL
+		    xmlTextReaderSetStructuredErrorHandler(xmlTextReaderPtr reader,
+							   xmlStructuredErrorFunc f,
+							   void *arg);
 XMLPUBFUN void XMLCALL            
 		    xmlTextReaderGetErrorHandler(xmlTextReaderPtr reader, 
 						 xmlTextReaderErrorFunc *f,