[rear-devel] [rear/rear] 25f86d: Update bootloader-functions.sh

[Johannes Meixner]

  Branch: refs/heads/jsmeix-grub2-config-cleanup
  Home:   https://github.com/rear/rear
  Commit: 25f86d4f9cb320db637e65550830cb19a7fd2b02
      https://github.com/rear/rear/commit/25f86d4f9cb320db637e65550830cb19a7fd2b02
  Author: Johannes Meixner <jsmeix at suse.com>
  Date:   2021-07-29 (Thu, 29 Jul 2021)

  Changed paths:
    M usr/share/rear/lib/bootloader-functions.sh

  Log Message:
  -----------
  Update bootloader-functions.sh

Set GRUB2 timeout to new config variable GRUB2_TIMEOUT that is by default 300 seconds.
Set GRUB2 default boot menu entry to GRUB2_DEFAULT_BOOT that is by default 'chainloader'
which should usually boot the original system and reference GRUB2 boot menu entries
by 'menuentry ... --id=...' to have meaningful names instead of meaningless numbers.
Sleep 3 seconds exactly before GRUB2 shows its menu (it replaces what there is on the screen)
so that the user has a chance to see possible GRUB2 (error) messages on the screen.