Disable netsplit detection in ircd-irc2

By default ircd-irc2 goes to netsplit mode if the amount of connected users or servers go below a certain limit.

Default limits are:
- less than 65000 users connected or
- less than 80 servers connected. 

This means that in practice all brew installed ircds are always in netsplit mode.

In netsplit mode no one can be channel operator. Channel operators are useful already in small ircd setups. Therefore it's best to disable netsplit detection. You need to administrate a popular IRC network with multiple servers for netsplit detection to be useful.
Nice to hear. Here is little more context. This is full documentation of the configuration option in question:

```
/*
 * Split detection
 * This defines default thresholds for turning on and off the split-mode,
 * where joins to new channels do not give chanop status.
 * This should always be bigger than the max counts of
 * users/servers in your TLD (or some other close group), so you
 * get in split when you split. It is also a good practice to set
 * around 90% of what your whole network counts minimally (servers
 * inside masks are also counted), so that splits of smaller parts
 * would be noticed on each side.
 *
 * Defining to 0 disables entering split-mode.
 */
#define DEFAULT_SPLIT_USERS     65000
#define DEFAULT_SPLIT_SERVERS   80
```