libfdisk: add info, warn and wanx Ask API

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: add callacks for info, warn and warnx Ask API

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: (gpt) use fdisk_{warn,warx,info} functions

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