The check to verify whether we've got the right GL context was
checking that the GL version was less than 3 whenever the non-GL3
driver is used. However it looks like the driver is free to return a
GL3 context that is compatible with GL2 if GL2 is requested so this
was breaking the GL2 driver.
This also adds the necessary SDL attributes to request a forward
compatible core context like the GLX and EGL winsys's do. I haven't
actually tested this because it looks like SDL will only create a GL
context with GLX and I haven't got a recent enough X server to handle
the glXCreateContextAttribs request.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit d46acafa3ea7ba2e6c4ac7a45f00a132df1b2872)
76843fc529