findpkgs: change coding style / 2x speedup

This modified findpkgs behave as the previous
version.. the diffs show no discrepancies

It can be faster, but requires more attention
to the details.

old
    time ./support/findpkgs-old &>/dev/null

    real    6m7.668s
    user    1m23.250s
    sys 2m11.517s

new
    time ./support/findpkgs &>/dev/null

    real    3m20.436s
    user    0m57.060s
    sys 1m5.267s