X11 + i915kms

[Hans Petter Selasky]

Hi Jan,

I've pushed some changes. Please verify (should work with latest 12.1 
and 12-stable and 11.3 and 11-stable):

    d7cd40063..6d68e697c  drm-v4.16 -> drm-v4.16
    f3206bf81..99da0bacc  drm-v4.16-fbsd12.0 -> drm-v4.16-fbsd12.0
    6706271dc..92a0a5d00  drm-v5.0 -> drm-v5.0
    eebd254ce..847921ac8  drm-v5.0-fbsd12.1 -> drm-v5.0-fbsd12.1

Relevant commits upstream:

https://svnweb.freebsd.org/changeset/base/357612
https://svnweb.freebsd.org/changeset/base/357613

--HPS