Patch for gbde(8)

Hi there,

I have some old patch for gbde(8).  It fixes some omissions
in the utility usage (and its style) and in the manpage.
Can someone using this utility please double-check that this
patch is still correct (it's been a while since I developed
it), and possibly commit it (if you have commit privilege).


Cheers,
-- 
Ruslan Ermilov
ru_at_FreeBSD.org
FreeBSD committer