fdisk: always print warning for mis-aligned partitions

This patch restores the original fdisk behavior and always prints
information about misaligned partitions in 'p'print output.

Signed-off-by: Karel Zak <kzak@redhat.com>
libblkid: (gpt) use real sector size to set PTMAGIC_OFFSET

So stupid and 5 years old bug...

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