i965/vec4: Implement VS_OPCODE_GET_BUFFER_SIZE

Notice that Skylake needs to include a header in the sampler message
so it will need some tweaks to work there.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
5 files changed