btrfs: add multi-statement protection to btrfs_set/clear_and_info macros

Multi-statement macros should be enclosed in do/while(0) block to make
their use safe in single statement if conditions. All current uses of
the macros are safe, so this change is for future protection.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>