check-va-api: Try to decode H264Main and fallback to MPEG2Simple
Some Intel GPUs don't have the profile "VAProfileNone".
For this reason we try "VAProfileH264Main" instead, that should be supported since Intel GMA 4500 and Radeon HD 2000 and GeForce 8.
For additional coverage we also fallback to "VAProfileMPEG2Simple", that has a similar GPU compatibility.
Fixes: #24 (closed)
In the end the patch is simple, but without the buffer size change I was getting an error about an invalid VAContextID
and it took some time to figure out where the issue was :/
/cc @smcv