Function randCopy item path

Returns a random u64 value comprised between min and max values (inclusive). Arguments 3 to 5 are unused.

Relies on rand() function from libc, so libc::srand() should be called once before this helper is used.

§Examples

extern crate libc;
extern crate rbpf;
extern crate time;

unsafe {
    libc::srand(time::precise_time_ns() as u32)
}

let n = rbpf::helpers::rand(3, 6, 0, 0, 0);
assert!(3 <= n && n <= 6);