paycheck: applier honors sparse holes

Up until now, paycheck's applier ignored sparse (aka pseudo-) extents
completely, except for REPLACE operations (where a sparse extent is an
indicator for a signature blob). This is now fixed.

BUG=chromium:221846
TEST=Passes integration test

Change-Id: I8b7fde6e4bb20912a59ce9a509a20c00c5c0751b
Reviewed-on: https://gerrit.chromium.org/gerrit/50558
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed