mtfxmldump: move XML writing into its own function

Change-Id: I82954177fe9d4934e69b33c1c985304add09e089

include/test/mtfxmldump.hxx

@@ -17,10 +17,14 @@
 #include <vcl/gdimtf.hxx>
 #include <vector>
 
+class XmlWriter;
+
 class OOO_DLLPUBLIC_TEST MetafileXmlDump
 {
     std::vector<bool> maFilter;
 
+    void writeXml(GDIMetaFile& rMetaFile, XmlWriter& rWriter);
+
 public:
     MetafileXmlDump();
     virtual ~MetafileXmlDump();