livepatch: Allow to override inter-modules buildid dependency

livepatch: Allow to override inter-modules buildid dependency

By default Livepatch enforces the following buildid-based dependency
chain between livepatch modules:
  1) first module depends on given hypervisor buildid
  2) every consecutive module depends on previous module's buildid
This way proper livepatch stack order is maintained and enforced.
While it is important for production livepatches it limits agility and
blocks usage of testing or debug livepatches. These kinds of livepatch
modules are typically expected to be loaded at any time irrespective
of current state of the modules stack.

To enable testing and debug livepatches allow user dynamically ignore
the inter-modules dependency. In this case only hypervisor buildid
match is verified and enforced.

To allow userland pass additional paremeters for livepatch actions
add support for action flags.
Each of the apply, revert, unload and revert action gets additional
32-bit parameter 'flags' where extra flags can be applied in a mask
form.
Initially only one flag '--nodeps' is added for the apply action.
This flag modifies the default buildid dependency check as described
above.
The global sysctl interface input flag parameter is defined with a
single corresponding flag macro:
  LIVEPATCH_ACTION_APPLY_NODEPS (1 << 0)

The userland xen-livepatch tool is modified to support the '--nodeps'
flag for apply and load commands. A general mechanism for specifying
more flags in the future for apply and other action is however added.

Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Andra-Irina Paraschiv <andraprs@amazon.com>
Reviewed-by: Eslam Elnikety <elnikety@amazon.de>
Reviewed-by: Petre Eftime <epetre@amazon.com>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Martin Pohlack <mpohlack@amazon.de>
Reviewed-by: Norbert Manthey <nmanthey@amazon.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>