Rename the file so that it is clear that the recommendations are x86-64
specific.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

Add a header that will make the checker script think that it is dealing
with a x86_64 config file. Additionally, update the stackprotector
related options to reflect the >= 4.18 names.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

It is needed only for kernels prior to v4.11 (Kees has updated the wiki)

This script helps me to check the Linux kernel Kconfig option list
against my hardening preferences for x86_64.

Nobody likes checking configs manually. Let the computers do their job!

Signed-off-by: Alexander Popov <alex.popov@linux.com>