Write a function named secondIndexOf that accepts an array of integers, its length, and a target value as parameters and returns the index of the second occurrence of the target value in the array.
If the value does not appear in the array at least twice, return -1.
For example, if an array called list stores the following values:
// index 0 1 2 3 4 5 6 7 8 9 10
int list[] = {42, 7, -9, 14, 8, 39, 42, 8, 19, 0, 42};
Then the call secondIndexOf(list, 11, 42) should return 6 because the index of the second occurrence of value 42 in the array is at index 6.
The call secondIndexOf(list, 11, 14) should return -1 because value 14 does not occur at least twice in the array.
