fix: NoClassDefFoundError on FastUtil's toIntArray

[Kambet]

Using IntCollection#toIntArray leads to
java.lang.NoClassDefFoundError: it/unimi/dsi/fastutil/ints/IntArrays.

If we look at fast util AbstractIntCollection code, we can see that it is using IntArrays class from the same package when collection is empty:

public int[] toIntArray() {
        int size = this.size();
        if (size == 0) {
            return IntArrays.EMPTY_ARRAY;
        } else {
            int[] a = new int[size];
            IntIterators.unwrap(this.iterator(), a);
            return a;
        }
    }

Velocity does exclude all IntArray* classes, which leads to IntArrays class being excluded as well.