* disk/dmraid_nvidia.c (grub_dmraid_nv_detect): Add start_sector

parameter.  Set its pointer target to 0.
* disk/mdraid_linux.c (grub_mdraid_detect): Add start_sector
parameter.  Set its pointer target to 0 for 0.9 metadata, or to the
`data_offset' value from the superblock for 1.x metadata.
* disk/raid.c (grub_raid_read): Offset reads by the start sector of
data on the device.
(insert_array): Record the start sector of data on the device.
(grub_raid_register): Pass start_sector parameters to
grub_raid_list->detect and insert_array.
* include/grub/raid.h (struct grub_raid_array): Add start_sector
member.
(struct grub_raid): Add start_sector parameter to `detect'.

disk/dmraid_nvidia.c

@@ -89,7 +89,8 @@ struct grub_nv_super
 } __attribute__ ((packed));
 
 static grub_err_t
-grub_dmraid_nv_detect (grub_disk_t disk, struct grub_raid_array *array)
+grub_dmraid_nv_detect (grub_disk_t disk, struct grub_raid_array *array,
+                       grub_disk_addr_t *start_sector)
 {
   grub_disk_addr_t sector;
   struct grub_nv_super sb;
@@ -145,6 +146,8 @@ grub_dmraid_nv_detect (grub_disk_t disk, struct grub_raid_array *array)
   grub_memcpy (array->uuid, (char *) &sb.array.signature,
                sizeof (sb.array.signature));
 
+  *start_sector = 0;
+
   return 0;
 }