If GRUB2 is not available in the system a fallback to install Extlinux
will happen. This patch also allows you to enforce the use of Extlinux
exporting the DIB_EXTLINUX variable.
Change-Id: I88fa792a0bd19cacca167134f2054b11c807a451
This patch is part of a another big patch that will implement a fallback
to Extlinux in case GRUB2 is not available in the system. The reason why
it's being splitted in two patches is because git is not being able to
recognize the file changes when the rename happens in the same commit.
Change-Id: Ic2027dfa057fd6d62b532203b7ff50c3c739bccb