refactor handover penalty timers

So far the list of penalty timers was stored for an opaque target
pointer. That was either a gsm_bts pointer for a local BTS, or a cell
identifier list pointer for a remote-BSS cell.

Reasons to refactor penalty timers:

- The cell identifier list pointer came from the neighbor configuration
  storage, but the way cell neighbor config is stored will change in a
  subsequent patch. There will be no more cell identifier lists there.

- Storing object pointers is inherently unsafe -- if an object gets
  removed and another gets allocated, the penalty timer could
  theoretically remain in force for an unrelated object.

Rather store penalty timers for specific Cell IDs. Since remote-BSS
neighbors can be requested by a cell identifier *list*, use a
gsm0808_cell_id_list2 as key in the list of penalty timers.

Fix handover_test.c: have different CI for each local BTS. So far it was
the same LAC+CI for all BTSes, which now would make the test fail,
because any penalty timer would appear to apply to all local cells.

Related: OS#5018
Change-Id: I72dd6226a6d69c3f653a3174c6f55bf4eecc6885
9 files changed