update-bootloader-rpm-macros-0-bp153.1.12

- avoid bashisms in update-bootloader scriptlets (bsc#1195391)

- Use grub2-instdev-fixup.pl if available for correting
  /etc/default/grub_installdevice to use disk device if grub has been
  installed on it

- Make sure _rpmmacrodir is defined to restore compatibility with SLE12

- make perl-Bootloader optional. This avoids to pull in perl in
  small systems that do not necessarily use perl-Bootloader

- Move RPM macros to %_rpmmacrodir.

- RPM group fixup

- New package with rpm macros to support bootloader update in %posttrans to
  improve the efficiency. (bsc#997317)