net-next build error (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    7b3ed2a1 Merge branch '100GbE' of git://git.kernel.org/pub..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17bf8fd8a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=182ab6ef38134502
dashboard link: https://syzkaller.appspot.com/bug?extid=21456e3ef58cde16e0fa
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+21456e3ef58cde16e0fa@xxxxxxxxxxxxxxxxxxxxxxxxx

./include/linux/netfilter_ipv6.h:110:9: error: implicit declaration of  
function ânf_ct_frag6_gatherâ [-Werror=implicit-function-declaration]

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.