It's possible to have several protocols per family which is a problem
with the current way the protocols are stored.
This allows to register a new protocol in HAProxy which is not a
protocol in the strict socket definition. It will be used to register a
SOCK_STREAM protocol using socketpair().
Building 1.6 and above on OpenBSD 5.2 fails due to protocol.c not
including sys/types.h before sys/socket.h :
In file included from src/protocol.c:14:
/usr/include/sys/socket.h:162: error: expected specifier-qualifier-list before 'u_int8_t'
This fix needs to be backported to 1.6.
