Enhancements to release.sh based on work done to generate-release.sh

- Parameterize out make
- Support OptionsNG
- Use shell built-ins for arithmetic instead of expr

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
More enhancements to improve release.sh

- Turn the checkout operations into functions
- Move the functions up to the top so they can be overridden
  by release.conf

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
Return ENETDOWN when the parent interface is down.

MFC after:	1 week
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' into kern-173932