btrfs-progs: use NULL instead of 0

These were mostly in option structs but there were a few gross string
pointer arguments given as 0.

Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/mkfs.c b/mkfs.c
index 5f8d8b5a..8b653593 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -381,7 +381,7 @@ static struct option long_options[] = {
 	{ "rootdir", 1, NULL, 'r' },
 	{ "nodiscard", 0, NULL, 'K' },
 	{ "features", 0, NULL, 'O' },
-	{ 0, 0, 0, 0}
+	{ NULL, 0, NULL, 0}
 };
 
 static int add_directory_items(struct btrfs_trans_handle *trans,