[MEDIUM] stats: disable complex socket reservation for stats socket

[MEDIUM] stats: disable complex socket reservation for stats socket

The way the unix socket is initialized is awkward. Some of the settings are put
in the sockets itself, other ones in the backend. And more importantly the
global.maxsock value is adjusted so that the stats socket evades the global
maxconn value. This complexifies maxsock computations for nothing, since the
stats socket is not supposed to receive hundreds of concurrent connections when
the global maxconn is very low. What is needed however is to ensure that there
are always connections left for the stats socket even when traffic sockets are
saturated, but this guarantee is not offered anymore by current code.

So as of now, the stats socket is subject to the global maxconn limitation just
as any other socket until a reservation mechanism is implemented.