Returns the client's frags.
While this is mod-independent, the mod may track frag count differently,
so it can only be retrieved using another native or other methods.
This will actually return the client's overall score, which may or may
not be equal to their scored frags depending on the mod.
Frags/Score of the client. Also returns 0 if the client is
not connected or the index is not within the range of
1 to MaxClients