Mario Kleiner authored Apr 30, 2018 and Adam Jackson committed Apr 30, 2018

Checking for dri3_screen_info_rec.version >= 2 is insufficient,
as some shipping drivers, e.g., intel-ddx, nouveau-ddx, set the
version to DRI3_SCREEN_INFO_VERSION, ie. to whatever version the
installed servers headers define. On server 1.20 that would
be version 2, but the drivers still don't support the v1.2
hooks. Make sure all hooks are defined before reporting v1.2.

Also make clamping of reported version to minimum of client
or server robust against possible future clients with possible
majorVersion >= 2.0.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Cc: Daniel Stone <daniels@collabora.com>