frontend/nine: Skip invalid swvp calls
Without this it may crash running wine tests. According to the test themselves, the correct behaviour is a bit more complicated, but that's a first step. cc: mesa-stable Signed-off-by:Axel Davy <davyaxel0@gmail.com> Acked-by:
David Heidelberg <david.heidelberg@collabora.com> Part-of: <mesa/mesa!18021>