gfxpayload support
* commands/videotest.c (grub_cmd_videotest): use grub_video_set_mode
* include/grub/video.h (GRUB_VIDEO_MODE_TYPE_PURE_TEXT): new definition
(grub_video_setup): remove
(grub_video_set_mode): new prototype
* loader/i386/linux.c (DEFAULT_VIDEO_MODE): new definition
(vid_mode): remove
(linux_vesafb_res): compile only on PCBIOS
(grub_linux_boot): support gfxpayload
* loader/i386/pc/xnu.c (video_hook): new function
(grub_xnu_set_video): support gfxpayload
* term/gfxterm.c (DEFAULT_VIDEO_WIDTH): removed
(DEFAULT_VIDEO_HEIGHT): likewise
(DEFAULT_VIDEO_FLAGS): likewise
(DEFAULT_VIDEO_MODE): new definition
(video_hook): new function
(grub_gfxterm_init): use grub_video_set_mode
* util/grub.d/30_os-prober.in: remove explicit modesetting before
loading xnu
* video/video.c (grub_video_setup): removed
(grub_video_set_mode): new function based on grub_gfxterm_init and
grub_video_setup
3eb5ed4ec0