Bug#956131: [live-build] boot failure, broken bootloaders when not using syslinux

[jnqnfe@gmail.com]

update:

1) from my notes, in fact I'd gone back as far as v5.0 confirming the
presence of the grub-pc failure.

2) I've noticed the presence of the fixed path '/live/vmlinuz' in
binary_grub-efi, and with a hack to have this replaced with the long
name '/live/vmlinuz-4.19.0-8-amd64' this also fixes the EFI side of the
problem, so that explains how the EFI stuff ends up checking that fixed
/live/vmlinuz' path and presents an alternate opportunity for a fix. It
seems the author of the EFI live-build functionality only tested it
with syslinux.