For each registered game, export an object on the bus under the
path "/com/feralinteractive/GameMode/Games/<pid>" with an dbus
interface of ""com.feralinteractive.GameMode.Game". The interface
currently provides to properties, ProcessId and Executable.
Additionally add the ListGames method and the GameRegistered,
GameUnregistered signals to the com.feralinteractive.GameMode
interface.
Return an array of pid_t elements containing the process ids of
all registered clients. Memory ownership is transferred to the
client and must be freed.
This is so it can out-live its membership in the client list, e.g.
when it is passed outside of gamemode-context.c and the reaper
comes along and reaps a client in the background but we still are
using the struct outside.
