Wireguard not compile, - udp: typedef udp tunneling functions to functions, not pointers

[Michael Pro]

https://reviews.freebsd.org/D36724
https://cgit.freebsd.org/src/commit/?id=bb77f0c2049311f0661c2493838d81a5a66c449c
#> uname -K
1400072

in wireguard-freebsd/src/if_wg.c:
rc = udp_set_kernel_tunneling(so4, (udp_tun_func_t)wg_input, NULL, sc);

change to:
rc = udp_set_kernel_tunneling(so4, wg_input, NULL, sc);