cros_generate_update_payload: support for user provided kernel/root paths

This is needed in order for a caller to be able to utilize the extracted
partitions after processing has completed, e.g. for verifying the
generated payloads.

BUG=chromium:243561
TEST=Partitions extracted to given paths; files preserved.

Change-Id: I6070596d5b7d6a16bbf8e1b37f7113a2c366bd8b
Reviewed-on: https://chromium-review.googlesource.com/181221
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed