[libxml2] Fix problem with specific and generic error handlers

[Daniel Veillard <veillard src gnome org>]

commit 890faa546bf386816dea59d0f1075bc3a42de263
Author: Pietro Cerutti <gahr gahr ch>
Date:   Mon Aug 27 13:24:08 2012 +0800

    Fix problem with specific and generic error handlers
    
    It seems that setting up both xmlTextReaderSetStructuredErrorHandler and
    xmlSetStructuredErrorFunc confuses the code around error.c:592 and following
    This patch works with any combinations of using xmlSetStructuredErrorFunc,
    xmlTextReaderSetStructuredErrorHandler, both, or none.

 error.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/error.c b/error.c
index 1c2fb36..6b7ef59 100644
--- a/error.c
+++ b/error.c
@@ -615,8 +615,11 @@ __xmlRaiseError(xmlStructuredErrorFunc schannel,
 	data = ctxt->userData;
     } else if (channel == NULL) {
 	channel = xmlGenericError;
-	if (!data)
+	if (ctxt != NULL) {
+	    data = ctxt;
+	} else {
 	    data = xmlGenericErrorContext;
+	}
     }
     if (channel == NULL)
         return;