btrfs-progs: fix argv0_buf handling

The variable argv0_buf was duplicated and the changes done in utils.c
were not propagated to help.c. So if an unknown commandline token was
found, the error message did not contain the known part:

 $ btrfs scrub test
 : unknown token 'test'

instead of

 $ btrfs scrub test
 btrfs scrub: uknown token 'test'

Signed-off-by: David Sterba <dsterba@suse.cz>

1 files changed, 2 insertions, 0 deletions

diff --git a/utils.h b/utils.h
index 12923de8..e7714821 100644
--- a/utils.h
+++ b/utils.h
@@ -235,4 +235,6 @@ static inline u64 div_factor(u64 num, int factor)
 int btrfs_tree_search2_ioctl_supported(int fd);
 int btrfs_check_nodesize(u32 nodesize, u32 sectorsize);
 
+const char *get_argv0_buf(void);
+
 #endif