meson: Prefer 'iris' by default over 'i965'.
This changes the default driver for Intel Gen8-11 hardware to be the newer 'iris' driver rather than the older 'i965' driver. To continue using i965, pass -Dprefer-iris=false when building. Reviewed-by: Jordan Justen <firstname.lastname@example.org> Tested-by: Marge Bot <mesa/mesa!3540> Part-of: <mesa/mesa!3540>
!3540 with iris-default in 20 minutes and 24 seconds (queued for 3 seconds)38 jobs for