program loading: add optional is_loader_active() callback

Add a way for a loader to indicate if it is active. Such users
of this callback would be vboot which can indicate to the rest
of the system that it isn't active. is_loader_active() also
gives vboot a chance to perform the necessary work to make
said decision.

Change-Id: I6679ac75b19bb1bfff9c2b709da5591986f752ff
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10022
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
4 files changed