resize_ffs improvements

[Adam Hamsik <haaaad%gmail.com@localhost>]

hi,

I have done some small improvements to resize_ffs. With [1] patch it ask for 
confirmation if user has run fsck on filesystem (requested by agc@) and I have 
changed default behaviour of tool to grow filesystem to device size by default, 
shrinking is still possible with -s parameter. I would like to commit this 
patch and add resize_ffs to release build to have at least ffsv1 grow/shrink 
working for users.

[1] www.netbsd.org/~haad/resize_ffs.diff

Regards

Adam.