screenshooter: Abandon recording rather than use unitialised format
screenshooter: Abandon recording rather than use unitialised format

Abandon the recording if the format is not known - this prevents the use of an
unitialised member is the header struct.

xorgy/weston,krezovic/weston,udoprog/weston,Fantu/compositor-spice,Tarnyko/weston-xdg_surface_present,krezovic/weston,kwm81/weston,eyolfson/weston,Gnurou/weston,udoprog/weston,Fantu/compositor-spice,mchalupa/weston,Gnurou/weston,giucam/weston,sir-murray/weston,jonnylamb/weston,eyolfson/weston,jonnylamb/weston,mchalupa/weston,kwm81/weston,Tarnyko/weston-xdg_surface_present,giucam/weston,sir-murray/weston,xorgy/weston,Fantu/compositor-spice