selftests/livepatch: introduce tests

Add a few livepatch modules and simple target modules that the included
regression suite can run tests against:

  - basic livepatching (multiple patches, atomic replace)
  - pre/post (un)patch callbacks
  - shadow variable API

Signed-off-by: Joe Lawrence <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
Tested-by: Miroslav Benes <[email protected]>
Tested-by: Alice Ferrazzi <[email protected]>
Acked-by: Joe Lawrence <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>
20 files changed