mkfs: refuse to initialize a misaligned device if not forced using libblkid

mkfs: refuse to initialize a misaligned device if not forced using libblkid

This is a new version of a patch to fix the problem about the usage of 4k
sector devices when the device is not properly aligned. It makes mkfs to
refuse to initialize a xfs filesystem if the -f option is not passed at the
command line, and forces a 512b sector size if the user chooses to force
the device initialization.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>