Add the ability to parse the processor architecture from the config file.

Change '-p' command-line argument behaviour. Now it comes with the
name of architecture you want to print recommendations for.

Currently only X86_64 is supported. More architectures to come soon.

This is based heavily on work by @tyhicks.

Create arch-dependent KSPP recommendations.
Thanks to @tyhicks.

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

The arm section of the KSPP Recommended_Settings wiki page contains the
following lines:

 # If building an old out-of-tree Qualcomm kernel, this is similar to
 # CONFIG_STRICT_KERNEL_RWX.
 CONFIG_STRICT_MEMORY_RWX=y

Since this option only applies to an old out-of-tree Qualcomm kernel,
it is not included in the config file.

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

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

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>

Thanks to @Bernhard40 for a nice idea.

The file indicates where you can find kernel configurations.