cros_generate_update_payload: respect TMPDIR and --work_dir

Makes it far more usable for cases where the hard-coded /tmp won't do.
It is named --work_dir for consistency with other tools (e.g. paygen).

BUG=chromium:253622
TEST=Works with both TMPDIR and --work_dir.

Change-Id: Iac9141018cd626a706570858652a468dff427901
Reviewed-on: https://chromium-review.googlesource.com/181222
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
1 file changed