It was missing in a previous change bab8741 (tree: use
TARGET_{CFLAGS,LDFLAGS} instead of the package default)

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

Tree is a recursive directory listing command that produces a depth indented listing of files,
which is colorized ala dircolors if the LS_COLORS environment variable is set and output is to tty.

Tree has been ported and reported to work under the following operating systems:
Linux, FreeBSD, OS X, Solaris, HP/UX, Cygwin, HP Nonstop and OS/2.

root@lede:/# tree -L 1
.
├── bin
├── dev
├── etc
├── lib
├── mnt
├── overlay
├── proc
├── rom
├── root
├── sbin
├── sys
├── tmp
├── usr
├── var -> /tmp
└── www

15 directories, 0 files

http://mama.indstate.edu/users/ice/tree/

Signed-off-by: BangLang Huang <banglang.huang@foxmail.com>