Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC 259016,259019,259049,259071,259102,259110,259129,259130,259178,259179,
259203,259221,259261,259532,259615,259650,259651,259667,259680,259727,
259761,259772,259776,259777,259830,259882,259915,260160,260449,260450,
260688,260888,260953,261269,261547,261551,261552,261553,261585:
Merge the vt(4) driver (newcons) to stable/10.

Approved by: ray

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

drm: Add missing bits to drmP.h, required by the Radeon driver

Some of the FreeBSD-specific definitions are moved to drm_os_freebsd.h.
But there's still work to do to clean it up and reduce the diff with
Linux' drmP.h.