The upcall_cost.py script has a useful port mapping cache that can be
very useful for other scripts.
Move it into a library file (usdt_lib.py). While we're at it, refactor
it into a class since setting attributes to functions and having it
return different types depending on input is not very clean.
This patch should not introduce any functional change.
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
