MFC r228192:

MFC r228192:
> Add a screen that asks if the user would like to enable crash dumps,
> giving them a very brief description of the trade-offs.  Whether the
> user opts in or out add an entry to what will become /etc/rc.conf
> explaining what dumpdev is and how to turn on/off crash dumps.  The folks
> who handle interacting with users submitting PRs have asked for this.
>
> Reviewed by:  nwhitehorn

Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/stable/9@228237 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f