spearmint: Actually set client numbers in snapshots

Appearently I forgot to add it. Server always sent zeros for local clientnums in snapshots.
Client parsing would convert index greater than snapshot numPSs to -1. So valid slots were 0, invalid were -1.

Caused issues for displaying client icons at vid_restart. Possibly other issues.

If local client was added at connect, the client number was sent in gamestate and appears to be fine.