fdisk: (bsd) cleanup label initialization

 - remove unused variables
 - cleanup code
 - use ask API

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: (bsd) use libfdisk to ask for label setting

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: (bsd) cleanup bootstrap install code

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: (bsd) use libfdisk for partition number dialog

Signed-off-by: Karel Zak <kzak@redhat.com>