Channel mode setting: The local server is allowed to work on local channels

Channel mode setting: The local server is allowed to work on local channels

Don't forbid the local server to change modes on local channels: this
happens when overriding modes on local (&) channels in the server
configuration file, for example, and is perfectly fine.

Without this patch, the server worked as expected but showed critical
error messages for each local channel in its configuration file:

  "Got remote MODE command for local channel!? Ignored."