Make the yumpkg5 module MUCH faster

benchmarked with a state with 52 packages

    before
    real 0m58.023s
    user 0m37.749s
    sys 0m10.262s

    after
    real 0m9.650s
    user 0m6.192s
    sys 0m1.728s

This now actually makes yumpkg5 faster than yumpkg!