net/rayfish: port to other 64-bit platforms

route_manager-0.2.13: sin_zero: [0i8; 8] against a [c_char; 8] field.
Fixed with [0; 8].

tun-rs-2.8.9: imports libc::KINFO_FILE_SIZE, which libc defines only
for x86. Fixed by setting kf_structsize from size_of::<kinfo_file>().
The size is 1392 on powerpc64le from both the C header and the built
libc rlib, and the kernel accepts exactly that value.

(cherry picked from commit e55dbd67304e77785efce0411b051a421bc03ded)

net/rayfish: restrict build to amd64

(cherry picked from commit dc96f05ced2eec58ee0db405de41c6bed201d2ce)