[$] Supporting UEFI secure boot in Debian

The Debian project can be accused of many things, but jumping too quicklyon leading-edge technology is not one of them. That can be seen in, among otherthings, the fact that there is still not a version of the distribution thatsupports the UEFI secure boot mechanism. But, as Ben Hutchings explainedduring his 2016 Kernel Recipes talk, such support is in the works, and itwill be implemented in a uniquely Debian-like manner.