make WriteXGraphicBlipFill declaration same to WriteBlipFill

Change-Id: Ie7947abdf2e8e951c94006aae259ed1d84558b73
Reviewed-on: https://gerrit.libreoffice.org/49892Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

include/oox/export/drawingml.hxx

@@ -195,7 +195,7 @@ public:
 
     void WriteXGraphicBlipFill(css::uno::Reference<css::beans::XPropertySet> const & rXPropSet,
                                css::uno::Reference<css::graphic::XGraphic> const & rxGraphic,
-                               sal_Int32 nXmlNamespace, bool bWriteMode, bool bRelPathToMedia);
+                               sal_Int32 nXmlNamespace, bool bWriteMode, bool bRelPathToMedia = false);
 
     void WritePattFill( const css::uno::Reference< css::beans::XPropertySet >& rXPropSet );
     void WritePattFill(const css::uno::Reference<css::beans::XPropertySet>& rXPropSet,