livepatch: Always check hypervisor build ID upon livepatch upload

livepatch: Always check hypervisor build ID upon livepatch upload

This change is part of a independant stacked livepatch modules
feature. This feature allows to bypass dependencies between modules
upon loading, but still verifies Xen build ID matching.

In order to prevent (up)loading any livepatches built for different
hypervisor version as indicated by the Xen Build ID, add checking for
the payload's vs Xen's build id match.

To achieve that embed into every livepatch another section with a
dedicated hypervisor build id in it. After the payload is loaded and
the .livepatch.xen_depends section becomes available, perform the
check and reject the payload if there is no match.

Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Andra-Irina Paraschiv <andraprs@amazon.com>
Reviewed-by: Bjoern Doebel <doebel@amazon.de>
Reviewed-by: Eslam Elnikety <elnikety@amazon.de>
Reviewed-by: Martin Pohlack <mpohlack@amazon.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>