blkid: recognize btrfs

Add btrfs detection to libblkid, now that the disk format should be
recognizable in the future.

# misc/blkid /tmp/fsfile
/tmp/fsfile: LABEL="mylabel" UUID="102b07f0-0e79-4b42-8a4e-1dde418bbe6d" TYPE="btrfs"

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2 files changed