Btrfs-progs: fix compile warning in is_ssd()

mkfs.c: In function ‘is_ssd’:
mkfs.c:1168:26: warning: ignoring return value of ‘blkid_devno_to_wholedisk’,
declared with attribute warn_unused_result [-Wunused-result]
  blkid_devno_to_wholedisk(devno, wholedisk, sizeof(wholedisk), NULL);

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-subvolume.c

The patch also fixes some coding styles problems.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-balance.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-chunk.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-dedup.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-device.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-filesystem.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-inspect.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-qgroup.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-quota.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-receive.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-replace.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-restore.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-scrub.c

There will be four kinds of return value for command "scrub start":

0: scrub dosen't find errors and return success.
1: failures.
2: scrub finds errors and correct all of them.
3: scrub finds errors and some of them are not correctable.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in cmds-send.c

If btrfs send return failure, we return 1，otherwise 0 will be returned.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in btrfs-imgae.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in btrfs-zero-log.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in utils.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in mkfs.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Btrfs-progs: fix magic return value in qgroup.c

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>