add an rc.d script to automatically grow the specified FS...  It has
been tested on both MBR and GPT...  It won't be enabled until you add
growfs_enable="YES" and will only run on first boot..


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273955 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f