[libxslt] Fix -Wformat-overflow warning (GCC 9)

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 949440522dfa7a26ad1dfd74330efc5dcddbb47b
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Mon Apr 22 12:50:53 2019 +0200

    Fix -Wformat-overflow warning (GCC 9)

 libxslt/xslt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libxslt/xslt.c b/libxslt/xslt.c
index a234eb79..5fda7604 100644
--- a/libxslt/xslt.c
+++ b/libxslt/xslt.c
@@ -1349,8 +1349,8 @@ xsltParseStylesheetOutput(xsltStylesheetPtr style, xmlNodePtr cur)
                        *  via the stylesheet's error handling.
                        */
                        xsltTransformError(NULL, style, cur,
-                           "Attribute 'cdata-section-elements': The value "
-                           "'%s' is not a valid QName.\n", element);
+                           "Attribute 'cdata-section-elements': "
+                           "Not a valid QName.\n");
                        style->errors++;
                    } else {
                        xmlNsPtr ns;