Fail to compile tnftp during install

FYI:
```
qblab@qblab-tape:~$ brew install ltopers
==> Installing ltopers from amiaopensource/amiaos

==> Installing dependencies for amiaopensource/amiaos/ltopers: tnftp, tree, xmlstarlet and mediamicroservices/mm/mm
==> Installing amiaopensource/amiaos/ltopers dependency: tnftp
==> Downloading https://opensource.apple.com/tarballs/lukemftp/lukemftp-16.tar.gz
Already downloaded: /home/qblab/.cache/Homebrew/downloads/1faa4668197613d2025e91fa19f8ff1a73539f7316a0888a26d8a9149e5c942e--lukemftp-16.tar.gz
==> ./configure
==> make all
Last 15 lines from /home/qblab/.cache/Homebrew/Logs/tnftp/02.make:
gcc-5 -g -O2 -I. -I./.. -I. -I.. -I./../libnetbsd -c sl_init.c
gcc-5 -g -O2 -I. -I./.. -I. -I.. -I./../libnetbsd -c strlcat.c
gcc-5 -g -O2 -I. -I./.. -I. -I.. -I./../libnetbsd -c strlcpy.c
gcc-5 -g -O2 -I. -I./.. -I. -I.. -I./../libnetbsd -c glob.c
glob.c: In function 'globextend':
glob.c:723:62: error: 'ARG_MAX' undeclared (first use in this function)
if ((pglob->gl_flags & GLOB_LIMIT) && (newsize + *limit) >= ARG_MAX) {
^
glob.c:723:62: note: each undeclared identifier is reported only once for each function it appears in
Makefile:29: recipe for target 'glob.o' failed
make[1]: *** [glob.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory '/tmp/tnftp-20200105-20353-7c2n5z/lukemftp-16/tnftp/libnetbsd'
Makefile:22: recipe for target 'libnetbsd.a' failed
make: *** [libnetbsd.a] Error 2
```

This issue has yet been reported in linuxbrew. Any idea?