GNUStep build: add glfilterreflectedscreen sources
GNUStep build: add glfilterreflectedscreen sources

mapmapteam/gst-plugins-gl,mapmapteam/gst-plugins-gl,ystreet/gst-plugins-gl,ystreet/gst-plugins-gl,mapmapteam/gst-plugins-gl,ystreet/gst-plugins-gl