Fix a failure to report xmlreader parsing failures

Related to https://bugzilla.gnome.org/show_bug.cgi?id=654567
the problem is that the provided patch failed to raise an error
on xmlTextReaderRead() return when an actual parsing error occured
diff --git a/xmlreader.c b/xmlreader.c
index 77ac71b..10417ee 100644
--- a/xmlreader.c
+++ b/xmlreader.c
@@ -907,8 +907,11 @@
 	}
     }
     reader->state = oldstate;
-    if (reader->ctxt->wellFormed == 0)
+    if (reader->ctxt->wellFormed == 0) {
 	reader->mode = XML_TEXTREADER_MODE_EOF;
+        return(-1);
+    }
+
     return(0);
 }