Roll libxslt to 891681e3e948f31732229f53cb6db7215f740fc7

third_party/libxslt/libxslt/xsltconfig.h.in

Index: third_party/libxslt/libxslt/xsltconfig.h.in
diff --git a/third_party/libxslt/libxslt/xsltconfig.h.in b/third_party/libxslt/libxslt/xsltconfig.h.in
index b4cac6d3219305f682cbcb2625447a9376713fe0..6e4e32850c9c6f29c91e0ded857155ee999a7766 100644
--- a/third_party/libxslt/libxslt/xsltconfig.h.in
+++ b/third_party/libxslt/libxslt/xsltconfig.h.in
@@ -153,6 +153,17 @@ extern "C" {
 #endif
 
 /**
+ * LIBXSLT_ATTR_FORMAT:
+ *
+ * This macro is used to indicate to GCC the parameters are printf-like
+ */
+#ifdef __GNUC__
+#define LIBXSLT_ATTR_FORMAT(fmt,args) __attribute__((__format__(__printf__,fmt,args)))
+#else
+#define LIBXSLT_ATTR_FORMAT(fmt,args)
+#endif
+
+/**
  * LIBXSLT_PUBLIC:
  *
  * This macro is used to declare PUBLIC variables for Cygwin and for MSC on Windows