Ref params for pango_extents_to_pixels
Ref params for pango_extents_to_pixels

* pango/Pango.metadata: mark ref params on ExtentsToPixels.

orion75/gtk-sharp,Gankov/gtk-sharp,akrisiun/gtk-sharp,sillsdev/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,antoniusriha/gtk-sharp,antoniusriha/gtk-sharp,orion75/gtk-sharp,Gankov/gtk-sharp,openmedicus/gtk-sharp,Gankov/gtk-sharp,orion75/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,Gankov/gtk-sharp,sillsdev/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,sillsdev/gtk-sharp,orion75/gtk-sharp,antoniusriha/gtk-sharp,sillsdev/gtk-sharp,Gankov/gtk-sharp,akrisiun/gtk-sharp,antoniusriha/gtk-sharp,Gankov/gtk-sharp,antoniusriha/gtk-sharp,openmedicus/gtk-sharp,sillsdev/gtk-sharp,orion75/gtk-sharp