screenshooter: correct output ordering of screencast recording when Y-flip is off
screenshooter: correct output ordering of screencast recording when Y-flip is off

The screenshooter encoder wrote the output from either top-to-bottom or
bottom-to-top, depending on the Y-flip setting, but wcap-decode only
decodes from bottom-to-top. Make the encoder always output from
bottom-to-top, to match the decoder, and flip the input (source)
according to the Y-flip setting.

Signed-off-by: Tomohito Esaki <4c85e224df8fe738583b6ee846788bcf4b1c8ba2@igel.co.jp>
Reviewed-by: Giulio Camuffo <65adf162ac3b23aefeb12d72b964c762bc76d738@gmail.com>

Fantu/compositor-spice,giucam/weston,Gnurou/weston,krezovic/weston,krezovic/weston,kwm81/weston,Gnurou/weston,sir-murray/weston,giucam/weston,Fantu/compositor-spice,kwm81/weston,Fantu/compositor-spice,sir-murray/weston