Use flag-based instead of hook-based video mode selection and "auto"
keyword.
* include/grub/video.h (grub_video_adapter): Changed 'setup' member.
(grub_video_set_mode): Changed prototype. All users updated.
(grub_video_check_mode_flag): New inline function.
* video/video.c (parse_modespec): New function.
(grub_video_set_mode): Parse flags and keywords.
Video multiboot support.
* include/grub/multiboot.h (grub_multiboot_set_accepts_video):
New prototype.
* include/multiboot.h: Resynced with multiboot specification.
* include/multiboot2.h: Likewise.
* loader/i386/multiboot.c (UNSUPPORTED_FLAGS): Support video flags.
(grub_multiboot): Parse MULTIBOOT_VIDEO_MODE fields.
* loader/i386/multiboot_mbi.c (DEFAULT_VIDEO_MODE): New constant.
(HAS_VGA_TEXT): Likewise.
(accepts_video): New variable.
(grub_multiboot_set_accepts_video): New function.
(grub_multiboot_get_mbi_size): Account for video structures.
(set_video_mode): New function.
(retrieve_video_parameters): Likewise.
(grub_multiboot_make_mbi): Fill video fields.
