[cairo] cairo-demo/sdl

[Mauricio Piacentini]

I posted a couple of days ago about the sdl demo, as it was not 
producing the correct results for me (blank screen). No one replied, but 
I could reproduce the problem in more than one setup. The SDL surface 
parameters are not correct, among other issues.

I reworked the example to make it create the SDL surfaces correctly and 
blit with alpha. But before I post a patch (it is a significant change 
from the current one) can anyone tell me if the current code works on 
his/her machine? If no one replies I will polish my patch and post it 
for review.

Regards,
Mauricio