btrfs-progs: check blocks when checking fs roots

btrfs-progs: check blocks when checking fs roots

Usually if we find a bad block during the extent tree stuff we will error out,
but if the bad block is in an fs tree and doens't have extents in it then fsck
may still pass even though the block was complete garbage.  So add the check
block logic to the fs root checking so we actually error out of fsck if there is
a bad block.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.cz>