filters/xsltfilter: fix FTBFS against libxml 2.13+

See: c011e7605d
Closes: https://mirror.git.trinitydesktop.org/gitea/TDE/koffice/issues/96
Signed-off-by: Alexander Golubev <fatzer2@gmail.com>

filters/xsltfilter/export/xsltproc.cpp

@@ -287,7 +287,11 @@ int XSLTProc::parse()
      * disable CDATA from being built in the document tree
      */
     xmlDefaultSAXHandlerInit();
+#if LIBXML_VERSION < 21300
+    // In 2.13.0 this global variable was made constant and claimed that
+    // it "hasn't had an effect for a long time"
     xmlDefaultSAXHandler.cdataBlock = NULL;
+#endif // LIBXML_VERSION
 
     if ((cur != NULL) && (cur->errors == 0))
 	{

filters/xsltfilter/import/xsltproc.cpp

@@ -287,7 +287,11 @@ int XSLTProc::parse()
      * disable CDATA from being built in the document tree
      */
     xmlDefaultSAXHandlerInit();
+#if LIBXML_VERSION < 21300
+    // In 2.13.0 this global variable was made constant and claimed that
+    // it "hasn't had an effect for a long time"
     xmlDefaultSAXHandler.cdataBlock = NULL;
+#endif // LIBXML_VERSION
 
     if ((cur != NULL) && (cur->errors == 0))
 	{